This is explained in my guide in my signature .

Go this this website:
www.systemrequirementslab.com and run the test for World of Warcraft: The Burning Crusade ( Even if you don't plan on getting the expansion pack it's good to check it because some updates might add better graphics or something. )

I checked it and it says you need:

64mb VRAM ( videoRAM )
A videocard that supports 2.0 Pixel shader or better


I checked your budget and this is one of the better AGP videocards I found within your budget: http://www.newegg.com/Product/Product.aspx?Item=N82E16814130083

I had this one and it's very good, it ran Oblivion on Medium-high, WoW on max, Battlefield 2 on high so it's good for what you plan on playing

There may be betters so look around befor you get the one I linked

-Zero

that would be a very good card for you to get, i have a BFG 6800 GS OC and it is very, very good, in my opinion anyway

please tell us the ratings on your power supply though because you need a fairly good one to power the geforce 6800

The game installation probably mandates it; although I'm not sure since I've never played the game myself .

http://www.tomshardware.com/2007/05..._money/page5.html#best_agp_card_for_under_100