Xpress200 integrated chipset, which has PCI-E.
Either
http://www.ncix.com/products/index.php?sku=33527&vpn=EN8800GS%2FHTDP%2F384M&man ufacture=ASUS&promoid=1088 or
http://www.ncix.com/products/index.p...E&promoid=1088 ought to work, but you may need a new power supply to power the new videocard, as I don't know what your current one is. The first one is not very high performance, but good value.
Also, add more memory.
http://www.ncix.com/products/index.p...o&promoid=1088
You might want to think about upgrading your computer.
http://www.ncix.com/products/index.p...6&promoid=1088 This is a very good deal, and it's all assembled. Just add OS and video card and you're set.