My advice would be a Creative board, with a Ge force chip in it, 5 series, i'm saving my money and waiting for a possible Creative GeForce 6800.
Make sure you buy a good brand board, non of that OEM crap, buy ASUS, Creative, Ati, something that inspires confidence in the brand, don´t be fooled by cheap boards that have the same Graphics chip that you saw in some other board by one of these constructors, buy something with brand, the performance of a OEM board can be lesse than half a good brand board. It´s money well spent.
i currently have a Creative Geforce 4200TI and i'm playing Half Life 2, 1024x768 with details at maximum level.
"Religious belief is the “path of least resistance”, says Boyer, while disbelief requires effort."