If it is anything like my Geforce 6100 onboard GPU, you would be lucky to run it at 20 FPS with 320x240 resolution. I'm assuming that by now you have already seen this.
Invest in a graphics card, if possible, assuming you have an AGP 8X or PCI-Ex16 slot in your computer. For AGP, a 9500PRO
is all you need. For PCI-E, eh, let's say an X600 series card
. No need to break the bank, but make sure you have all the wires you need.