Re: What to upgrade?
your system looks fine as it is now, but if you do feel you need an upgrade, try the E8400, and the 3870 x2 combo. i personally don't see the need for sli boards/cards as a single $400-500 card can do more than enough. if your friend scores 1000 more points in 3dmark, that only a few fps more in actual games that he's getting.
it also depends on how "future-proof" you want your computer to be. in this case, try a ***ddr3*** board, with some nice ****ddr3 ram****.