The Radeon 9100 has 128MB video ram, but is, as I read here:http://graphics.tomshardware.com/graphic/20040211/
an integrated graphics card; this means you may need to adjust your playing options(I am assuming you have around 512RAM installed on your computer and the correct version of ActiveX):
Here are a couple of things to try.
1. Change your game settings to "best performance;" these settings should be somewhere in the Game Options tab.
2. Go to the ATI site and look for drivers specifically for your video card, download and install them.
And NOTE this about Open GL:http://www.ati.com/support/infobase/4232.html
Hope this information helps.