The two best PCI video cards I could find are:
VisionTek Xtasy 9200 SE 128MB PCI Video Card- $79.99-$99.99
PNY GeForce™ FX 5200 128MB PCI Video Card- about $119.99
I would recommed the PNY Geforce TX 5200, as it is fast than the other card and only a little bit more expensive. Upgrading your MOBO is very time consuming (you may have to reinstall your OS) and expensive ($100-$130 for the board, possibly more for new memory/processor), so you might not want to do it. If you really want to and don't want to get your hands too messy, you should buy an nForce 3 board. They come with an integrated video (DX8/9 compatible, I believe) and the best integrated sound in the business (as good as a SB Live!) and it comes in a convenient, low priced package which is easy to configure (it comes with an open AGP slot for a new card). As an added bonus, it costs just a little more than a regular MOBO without such features.
Sorry for the longwinded response, but at one time I did a lot of research into computers and video cards before I bought my own!