You're never too young to start retirement planning. Ask your employer what type of 401k plans they have to offer and if they have matching contributions. Your 401k plan is “pre tax” money and not considered your income. It will continue to grow and isn't subject to taxing until you withdraw your funds. There are limits however, as to how much you can defer or put towards your 401k plan.
For 2006, the limit is $15,000. However, if you are over the age of 50, you are given a limit of $20,000. You should make sure that your company is contributing or matching your 401k plan with cash dollars, sometimes they will match your plan with stocks. If you aim for cash in your retirement, then double check with your employer.