The reason everyone picks socket 939 motherboards instead of socket T is because the AMD dual core processors litterally wail on the P4's until they will never see living daylight. So, you have to pick a motherboard that is compatible with the wonderful processors we're showing you.
i'm a little over-budget so trimming ideas are more than welcome. the CPU seems a bit much right now, particularly since i don't mind going with something budget for now and upgrading later. again, expandability is the key for me on this build. TIA
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 http://www.newegg.com/Product/Product.asp?Item=N82E16813130491
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 power supply.
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