I did a lot of research of cards when I built my rig a few months ago and Nvidia have ATi covered in all ranges below the top of the range cards. The only decent cards ATi produce are the X1950s at the very top of the range. I was originally planning to get what was then an X1600 Sapphire Pro but was told that whole range was pants and that the 7600 series had ATi all the way through that range and the range below (7300). So I have a 7600GT by BFG and I am very happy with it.

Which brings me onto another point, the monitor. I have a 19" widescreen LCD which makes the most out of my graphics power and gives me really crisp and sharp detailing. Make sure you get at least a 19" and if possible widescreen! And if you are wanting gaming Core 2 Duo CPU plus 2GB RAM is a must.