looks like you really want alot of performance, I would say if you want a 64 bit processor, you don't have much options, and the 3000+ is the least expensive of these, it's what I would get aswell.
9600XT is very good, I reccomend this card, not too expensive like the 9800's.
yes I would say getting a 450W PS is a highly good idea.
also, with that many high performance parts, you will most likely need good cooling; prolly go with Thermaltake for this.
basically I don't know what is a good price in $US (I live in Australia)