are you going to be overclocking the CPU?
if so, i'd recommend the DFI Nf4 Ultra-D
it is less expensive than the Asus board, but about equal in overclocking potential.
but if you are not overclocking, I would suggest the MSI K8N Neo4-F
that is a great board. it still has descent overclocking potential. not as much as the Asus or DFI board, but is less expensive.
i would suggest this
it's constant output is 450W but can go higher if necessary (although you probabbly won't need it to)
it is a high quality but not so expensive PSU
Nvidia 7300 GS
performs nearly as well as the 6600 GT and costs $65