Bottom line, you want to put money into retirement accounts to take advantage of the significant advantage of compounding your retirement savings tax free over your working life.
Every extra $100/month that you can invest over 40 years (assuming a 10% return) will be worth about 650K to you!
Think of it this way... Would you rather build your poker bankroll on a rakefree table for as long as you could (knowing that in 40 years you'd have to go back to a raked table), or on a table with standard rake structures?
Recent IRA threads...
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Other links...
Money - The IRA Advantage
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Yahoo Finance IRA Special edition
Roth IRA Web Site
About.com Retirement planning
Investopedia retirement center