I want to install an agp graphic card, just wanted to know which is better ATI or NVIDIA?

its up you their isn't really a big difference i know people that swear by both! I prefer the NIVIDA iv got the 6800 with 512MB ram. thay made a few bigger for agp but since agp is going out of stile anyone that has one of the bigger ones probably won't want to get rid of it. and the last i knew most of the bigger game titles where developed and tested on nivida cards. my 6800 has been good to me but in the end its up to u PRICE, PRFORMACE,AVAILABILITY good luck!