The flip side of aggressiveness is losing your retirement. If you want to do some research, get A Random Walk Down Wall Street by Burton G. Malkiel or Common Sense on Mutual Funds by John C. Bogle. The former is comprehensive and the latter is an easy read. Both are considered classics. You might also want to solicit advice on the Vanguard Diehards forum http://www.diehards.org/?ndays=10. A number of well known financial authors (Rick Ferri, William Bernstein, Taylor Larimore, and Larry Swendrow) post there.
Also, take a look at the 2006 tally: http://www.tsptalk.com/utilities/tally_122906.pdf. Some TSPers beat the L2040 (32%). However, most (68%), including myself, did not.
In any event, Good Luck!
Thanks for those reading suggestions and for the Diehard site!