Actually, the motherboard/BIOS should detect the PCI video card and automatically disable the integrated video (and not grab part of the memory). If it does grab the memory still, then I would recommend checking for an updated BIOS. The latest BIOS for the Dim2350 is version A02 from July 2003 (http://support.dell.com/support/downloads/...mp;fileid=70067).
I definitely agree with using an existing PCI card instead of going out and buying one. While you can buy them still, the fact that not many people use them any more might actually drive the price up (since they are getting hard to find). If you don't have one, I'd recommend checking with whoever your "computer geek" friends are since, like me, they probably have a box of old hardware that they just haven't gotten around to throwing out.
Larry
Dell Customer Advocate