I just upgraded from a AMD 6400+ x2 to a Phenom II x4 945(110$)(Open box NCIX ebay)
and I upgraded from a 9800GTX to 2 GTX 460 1gb in SLI(330$)(Palit 165$ with MIR and MSI 165$ open box from NCIX ebay)
my Extreme vantage score went from X2441 to X12841 :)
no intel because I am semi poor and I didn't want to change motherboard(which I orginally got because it was cheap and bundled with a 3.2Ghz dual core) but the phenom II isn't too bad, certainly the weakest link with the 800mhz DDR2 ram
But ya, SLI everything running max(some drops in processor intensive stuff and cept for some DX11 stuff) tons of AA decent 1920x1200 resolution. i love metro 2033
Check out my custom cooling job ;)