In a recent article, I explained how almost anyone can become a millionaire, given sensible investments and a fair amount of time. Little did I know that one of my Foolish readers would write in to offer living proof.

The reader explained that he amassed a net worth of $1.5 million by socking away some $5,000 per year for 25 to 30 years in a retirement account, and by taking advantage of his employer's profit-sharing and stock investment plans. He said that much of his money was in the Fidelity Balanced Fund (FBALX), and that overall, his portfolio averaged about 8% to 10% per year. His final thought? "It wasn't rocket science."

It sure isn't. When I visit a compounding calculator, and enter $5,000 per year growing at 9% for 30 years, I end up with a rather hefty $743,000. But that only represents about half of his nest egg. What gives? For one thing, his employer was also kicking in its own contributions, which obviously makes a huge difference in the long run.

Do some digging
An online service called BrightScope rates numerous companies' retirement plans according to overall quality, company generosity, investment menu quality, and more. Here is a smattering of ratings for several of the Dow component companies:

Company

Overall Quality

Company Generosity

Investment Menu Quality

Boeing (NYSE: BA)

82

Great

Average

AT&T (NYSE: T)

73

Great

Average

Intel (Nasdaq: INTC)

76

Poor

Great

3M (NYSE: MMM)

72

Average

Poor

Chevron (NYSE: CVX)

85

Great

Average

McDonald's (NYSE: MCD)

57

Above Average

Great

Wal-Mart (NYSE: WMT)

48

Average

Average

Data: BrightScope.

A big difference
If you don't think your employer can make much of a difference, look more closely at BrightScope's ratings. The site compares each rated company with the top-rated company in its peer group, then shows what impact any relative shortcomings in its retirement plan may have for workers there.

For instance, take Wal-Mart. BrightScope asserts that the 40-point difference between the world's biggest retailer and its peer leader translated to 19 additional years of work, and as much as $160,000 in lost retirement savings, according to its calculation methods. In other words, if your company doesn't provide top-notch benefits, you might end up with a considerably smaller nest egg, and a far lengthier career than you'd like.

Look closely when comparing companies' retirement benefits. If you're contributing $5,000 per year to a 401(k) plan, an employer that matches 50% of those contributions will kick in an additional $2,500 per year. Invested annually, that extra amount will yield more than $370,000 if it grows at 9% for 30 years.

Don't neglect your retirement savings and end up a victim in this brutal economy. Always consider what a prospective employer will do for you to help you save for retirement.

For clear guidance, try our Rule Your Retirement newsletter free for 30 days -- it even recommends promising stocks and funds. Click here to get started today.

This article was originally published on Aug. 5, 2009. It has been updated by Dan Caplinger, who doesn't own shares of the companies mentioned. Intel, 3M, and Wal-Mart are Motley Fool Inside Value choices. Motley Fool Options has recommended buying calls on Intel. Try any of our investing newsletters free for 30 days. The Motley Fool is Fools writing for Fools.