I haven't bought a video card in a while so I haven't really looked at them much lately. My bud wants to upgrade and he has an off-the-shelf system but it has surprisingly decent specs and a PCIe slot. However, it has a pitiful 2D Intel card (onboard?) and only a 250W PSU. He picked out a pretty nice Diamond HD3870 card but I had to give him the bad news, requires a 450W PSU. He's a cheap bastage and doesn't want to upgrade his PSU. I'm running a Corsair 620W and I tried to talk him into it but no go. So, what's the best performance I can get for him without killing his PSU? I'm especailly a fan of Diamond, Asus and of course, ATI branded cards.
Thanks a bunch for any responses!
MC

Hardly anything, really. What is his CPU and number of hard/cd/dvd drives?

UPdate: I did the upgrade for my bud and it went well. I ended up giving him a fan 'cause the case fan it had was WEAK. He'd diggin' his upgrade and is gaming like mad.

The point of this though, is that I was surprised to open up his case and find an Asus motherboard inside! The model # doesn't show up on the Asus site so apparently it's one manufactured for HP, but still quality stuff nonetheless.