currently intel have the est enthusiast OCing chiset x48, if you still want SLI, go for the gx2 on it, but id recomed you just get one 3870x2 (and then pair it up with a 3870 after more pricedrops )
oh and sam, people have discoverd why the E8400s (well some not all) were crapping out at high clocks. its casu they were giving them the voltages that were being used for 65nm chips at those clocks. you can get the E8400 to 3.8 with stock voltages (on a good air cooler) but ppl wernt testing that.
I'd go for a pair of normal 3870s instead, that way you won't run into issues if a game doesn't support crossfire - which is very important. And before you mention it, the GA-P35-DS3P does crossfire for not too much cost. As for the E8400 I already knew it was voltage from the get-go, but you can't get up to 4Ghz+ on stock voltage.