The difference between the AMD Phenom II X6 and the AMD Phenom II X4 is only $40...I don't see why I shouldnt just go for the 6 core.
jaguarskx has already told you. No games out there in the market for now, take advantage of 6 cores. This is the beginning of the 4 core generation.
Phenom X 6 can be handy, only if there are apps or games, that make use of 6 cores. But currently there aren't any. http://www.techreaction.net/2010/05/06/amd-phenom-ii-six-core-1090t1095t-thuban-review/