GX2 is essentially 2 8800GTs. And as much as i love Asus motherboards, i heard that p5n-d isn't very good for overclocking but if thats your budget then i guess you would have to go with it, i would recommend 750i FTW from EVGA since i've heard some good stuff about it but i aren't really sure. honestly, by all means, try the asus, usually Asus motherboards yeild pretty good overclocking results. I would go with a 9800GX2 if you can find one for about $300, if not, you can go with a 8800GTS 512mb. PSU, HX620 from Corsair but that just might be a bit tight and to give it headroom, you can get an Antec Quaddro 850W. Both are modular so less cable hassle for you.