agree on :2500+
Mainboard: A7N8 deluxe(+SATA150,Firewire to A7N8), it supports dual channel DDR400, 5.1audio, 6 usb2.0, agp8X.
Memory: 512MDDR400
if you got 256M RAM for now, you would have to throw it away when upgrading.
I used 512M RAM for over 2 years, I don't think 256M memory would work fine with current applications. So 512M is a basic option, 1G is a good choice.