I am new to fooldom, having read the Motley Fool Guide. I have about 9K in conventional IRAs and another 7K in a SEP IRA. I am 42 and am in a position to put away 10 to 20K a year for the next 20 years. I'm interested in what I can do to move that money into stocks. I didn't know there were self-directed IRAs that allowed stock investing. What are the down sides of stock investing inside an IRA? Where can I go for more information on self-directed IRAs?

I am self-employed so the tax benefits of the SEP IRA are substantial but my calculations indicate that even without the tax benefits I come out way ahead investing in the Foolish Four.

Even with a 40% tax hit on my initial investment and 20% capital gains tax on any growth I figure that I will match the performance of an index fund in an IRA with anything over 16% return on stocks.At 20+% I come out WAY ahead. Has anybody else done this comparison? Is my math right?