That CPU will never keep up with an X800 xt, get a 9200SE instead...
Sorry, but thats about the third fastest CPU on the planet (Not including intel, which I don't). I know people keep going on about bottlenecking, but its not that drastic. Anyway, CPU bottlenecking isn't the major issue people make it out to be, unless you are using a PIII or something.
And yeah, you will want a 450+ psu with that lot, to keep it nice and stable.