a good 400-500 watt would work and give you enough power to expand..
Get a decent one.. you will pay a bit more but your paying for effeciancy and reliability.
and check to see if your video card has a addon power spot/plug.. it might need more power to use all of it at full speed
I have a HP a450n and I just added stick of 512 ram so now my im up to 1GB and I also added a new graphics card, a gefore 7600gs. My problem is that when i play a game of any kind, some kind of box comes up saying something about i need more power in order to fun the card properly or something like that. so i was wonder if i need a new power supply. the one i have right now is 250W. i was think about something around 400W becuase later on i might want to do more upgrading. And i also want to know which kind i should get so that it complies with my system.