Which PSU to buy?

[cmeyvin]

My current specs are:
Intel Pentium D925 3ghz dual core
Mb: Intel D946GZIS(946GZ express chipset)
ram:512mb 533mhz
PSU: FSP 250Watts
GPU: Gainward 9400gt 512mb

am planning to upgrade to:
GPU:Radeon HD4870 512mb
RAm:2x2gb 800mhz ram
and vista ultimate 64bit

Which psu should i buy which will be compatible with my pc parts?

[123456]

Almost any new ATX PSU will be compatible. I recommend at least a 550W PSU...