the x800 xt is gonna suck a lot of juice, especially because it draws power directly from the PS (through an attached power connector). Combined with all yer other junk, yer gonna suffer with a 350w PS.
I always recommend no less than 400w, and you can't hurt getting higher. There's no drawbacks to having the biggest powersupply you can find (aside from the drain on yer wallet). I run a 620w PS in my box.