There are software programs and websites, 800 numbers and glossy brochures. Companies dump avalanches of information on employees enrolled in 401(k) retirement plans. But employer-sponsored educational materials only tell one side of the story: the employer's. It's still up to workers to figure out whether a company plan meets their needs.

 

For many, that's not easy. As Rona Crystal discovered when she joined her current employer, a Boston publishing firm, people are desperate for independent guidance. When Crystal's co-workers realized the 54-year-old Brighton resident knew her way around a portfolio, she became the go-to person for anyone with questions about the plan.

 

''People knew I had invested in mutual funds for 30 years,'' said the database programmer, whose first job was with a fund provider. ''I must have had a dozen or more people coming to me for advice on what to invest in.''

 

Most American workers are no strangers to the 401(k): last year an estimated 42 million participated in their company's plan, according to the Investment Company Institute. The plans hold approximately $1.9 trillion in assets.

 

While a colleague like Crystal can be an enormous help in understanding investment options, she shouldn't be your first resort. Before quizzing a savvy-seeming co-worker, specialists say, vet your plan for three basic problems: an excess of company stock, insufficiently diverse offerings, and high fees.

 

Many small investors began scrutinizing their 401(k) plans in late 2003, when government regulators charged several major mutual fund firms with improper trading. The independent investment research firm Morningstar lists 22 under investigation. If your plan includes funds from Excelsior, Janus, Putnam, or one of 18 other companies on Morningstar's list, it's time to ask your human resources department some hard questions.

 

''If the fund families that have been implicated in the news are still being offered as options, it would be a good idea for the participant to make an inquiry to their employer as to whether they were discussed by the investment committee as still being appropriate,'' says Donald Trone, president of Pittsburgh's not-for-profit Foundation for Fiduciary Studies.

 

For Sidra Coleman, an accounts payable manager living in Nahant, it's all about the match. When Coleman, 53, was evaluating her current plan, she was more focused on the size of her employer's contribution and the waiting period for participation than any anything else.

 

''I worked for a company that lost a lot of money and stopped the match,'' she says. ''I just wish they wouldn't make you wait for a year to start getting the benefit. A whole year -- that's a whole year that you could be putting some money towards saving to retire.''

 

That waiting period puts Coleman's firm in the majority. In a 2003 survey of 489 employers by human resources consultants Hewitt Associates, employees were immediately eligible to participate in 43 percent of 401(k) plans.

 

That's a substantial increase over the 35 percent that allowed immediate enrollment in 2001. The amount of the match is fairly standard, though. Hewitt found that the majority of employers -- 73 percent -- contribute 50 cents per employee dollar, on up to 6 percent of pay. Roughly one-third of plan sponsors in Hewitt's survey provide their match in company stock, and only one-third of those allow participants to diversify at any time.

 

The good news is that employers are moving toward allowing employees to diversify. Hewitt saw a more than twofold increase in companies moving in that direction since 2001. The bad news is many employees have yet to take advantage of this right. More than one-quarter of the employees Hewitt studied had half or more of their 401(k) plans invested in company stock.

 

Investing heavily in company stock is one of the biggest mistakes you can make, according to Greg Gostanian, a partner in the Boston career management firm Clear Rock Inc. ''People don't invest in the other vehicles that are offered,'' he says. ''They put all their money in the company stock. That's a huge mistake. Huge.''

 

Investing in your employer's stock is like putting all your eggs in one basket, say investment specialists. ''The risks are very high given that your very livelihood is tied to the fortunes of the company,'' says Christine Bend, associate director of fund analysis for Morningstar. ''I would say 10 percent or less, preferably much less,'' should be invested in company stock.

 

Your company's plan should provide a variety of investment options. Besides US stock funds, you should have access to foreign stock funds, bond funds, and money market funds, according to Morningstar.

 

''You run into plans that have gaping holes,'' Bend says. ''Most plans will have stock and bond exposure, but occasionally you'll have a plan that won't have small-cap exposure.''

 

Your plan should include at least one index fund, which simply aims to provide the same performance as the S&P 500 or another major index, and several actively managed funds, or funds whose holdings are bought and sold to promote maximum growth. Your plan's assortment of actively managed funds should also be diverse in their holdings.

 

One of Crystal's main gripes with a former employer's plan was that all the growth funds had basically the same composition. ''The growth funds were all the same,'' she says.

 

Many employers are providing a wider choice of funds than in the past. Hewitt found that the average plan offered 13 different options in 2003, up from 12 in 2001. But such diversity brings with it the need for vigilance.

 

Trone believes a large selection of funds can even be a warning sign that your employer isn't vetting the options carefully. By presenting a huge array of possibilities, they essentially push the burden of diligence onto workers.

''When I see a situation where you've got a lot of funds, my first question is whether [the employer is] actually performing a duty to prudently select investment options,'' Trone says. The employer ''may be taking the position that by offering more they've reduced their liability, because the probability is that at least some of the funds will work.''

 

The fees charged by actively managed mutual funds have been making personal finance news lately, and no wonder. As the Dow Jones index falls, fees become proportionally more significant. The percentage your fund manager takes off the top is more noticeable when your returns are small to begin with.

 

This is of particular concern if, as some specialists believe, double-digit returns are a thing of the past. Burton G. Malkiel, author of ''A Random Walk Down Wall Street,'' predicts modest returns will continue for some time, making fees a bigger chunk out of the pie.

 

''Fees are the crucial element,'' Malkiel says. There is a big ''difference between a very low fee and a 2 percent a year fee, which is not at all uncommon in most mutual funds when you add the management fees to the transaction costs.''

 

In fact, Malkiel adds, fees are often inversely proportional to performance. Index funds, whose fees tend to be measured in fractions of a percent, usually outperform actively managed funds. ''The most certain way of getting top-quartile mutual fund performance is to have bottom-quartile fees,'' he says.

 

How do you know if you're paying too much? Estimates on appropriate fees vary. Malkiel believes the expense ratio for an actively managed fund should be no more than .5 percent. However, the Foundation for Fiduciary Studies reports that the expense ratio for large-cap growth funds averages 1.47 percent.

 

If you believe your plan isn't what it should be, lobby your benefits manager to make changes. First, though, you should educate yourself -- and not just by asking co-workers, as Crystal's colleagues did. Several years ago Crystal joined the American Association of Individual Investors, and she says it's proven invaluable. The organization regularly sponsors lectures by noted investment professionals.

 

Making a change to a 401(k) plan takes time -- up to a year once your employer has decided to act. Meanwhile, Bend says, don't look at your plan in isolation. Weigh it as part of your family's overall investment portfolio.