ditch the 3500, get a 3000 venice for 100 less and overclock it to at least 3300. if it won't overclock, oh well, 500 mhz is negligible.
You really need to think about the sli thing. is buying 2 cards worth it, really? sli is finicky, game dependent on improvement, and requires nvidia to produce new drivers for each new or old game supported (crossfire has its disadvantages too). 6800 gt might be a better way to go until next years upgrade. Or do the gigabyte 2 gpu on one card deal.
there is an antec true power 420? that should cover you. very robust.
I don't do cases. theyre just tin boxes to hold the good stuff.
why not water cooling? i have not seen anyone in here take the plunge yet (pun intentional).
why only 36 gig on the hd? and are you sure you want a 10,000 rpm vacuum cleaner/bomb in your system?