New video card for HP Pavilion 525c

Yeah, my computer is older than the hills.

OS: Microsoft Windows XP Professional (5.1, Build 2600)
System Model: DD210A-ABA 525C
Processor: AMD Athlon XP 2600+, MMX, 3DNow, ~2.1GHz
Memory: 448MB RAM
Page File: 648MB used, 1081MB available
Video Card: NVIDIA GeForce4 MX Integrated GPU

Lately my screen's begun to go black, and flash back on with everything blurred and all the colors distorted. The computer then locks up and the only way I can get it to respond is by unplugging and rebooting. My dad says it's the video card and I'm inclined to believe him.

I play world of warcraft, and I'm trying to find a decent card that'll fit my computer and run that game fairly well. It'd be a HUGE bonus if it was able to run Fable I as well, as my current vc is unable to.

Price is definitely an object, I am broke as hell, and have only $25 to my name. Should be getting some more soon though, I'd prefer a card under $100 if at all possible.