Question regarding Geforce 9800 GT superclocked edition

I've just purchased my fiance the EVGA Geforce 9800 GT superclocked edition as an early Christmas gift. We've just finished installing it and started up some of our games. The main game that we play is World of Warcraft which with our old card (Radeon x1650) got around 20FPS in big cities. Now that we've installed the new card, it's only getting around 10FPS in the big cities. Also, he booted up Team Fortress 2 and he was getting significantly less there too.

His system specs are as follows:

1. Motherboard - ECS Alphion
2. Graphic interface - EVGA Geforce 9800GT superclocked
3. Memory - 2GB DDR ram
4. CPU - Pentium 4
5. CPU Speed - 3ghz

I don't know the make of the power supply but I do know that it's 500W. If this information is needed, we can pop it open and get it.

From what I've read on the card, it should be a pretty good upgrade compared to what he has in there right now. I would think it would at least perform at the same speed as his current card if the CPU wasn't strong enough. I'm not understanding why it is performing so badly. Could his CPU be causing the graphics card to bottleneck?

If there's any further information you need, please ask. I'd hate to have to return it to the store since it appears to be a very nice card according to reviews.

Do you have the latest drivers installed? And have you confirmed if the low FPS are not due to your internet connection?

Yep, the latest drivers were installed.

I had a thread going on another board and it appears it's the PSU causing the issues. We're picking up another one in a couple of hours, so hopefully that will take care of everything.