Re: Need advice..
I don't exactly know what "terrible performance" is, but it looks like it's suffering from the graphics card. The 7600GT is more powerful than the 8400GS.
EDIT: Ah, just read the part about 2 of them. Shouldn't make a huge difference; usually it's best to have 1 powerful card as opposed to 2 weaker cards SLI'ed. Few, if any, games get truly doubled performance.
ASUS A8N32 SLI-Deluxe, AMD Athlon X2 3800+ @ 2.8GHz, eVGA 8800GTS 320MB, 2GB Corsair XMS DDR400, 160GB WD HDD + 320GB Seagate Barracuda 7200.10, AC Freezer 64 Pro, 700W OCZ GameXStream, NZXT Zero :D
I think I've decided to leave... maybe I'll come back sometime.