Have a dell P4 with 7600GT PCI-E
I have a strict 250$ to spend including shipping.
If I get 6 decent months out of it I will be happy then I can start over.
I have a non-dell case around and will keep HDD and Burner for now.
I need MB/CPU/Memory and PSU.
I am not expecting much for this amount but help me get the most out of it.
The AM2 Mobo will support the Phenom when it ships to give an upgrade path.
If you have spare cash to finance rebabtes, you could get some better memory but they have $30-$40 Rebates to drop the price to $61
There is also a very nice 550w Antec that normally goes for $99 that has a $30 instant rebate with a promo code and has a $30 Rebate for a final proice of $39, but the extra advance cash will take you over $250 w/shipping.
If It was between the memory and the PSU, I would go for the 550 Antec since that will support really nice GPUs easily for future upgrades.