Dang, Skuzzy beat me to it. The difference is the PCI card. it just can't perform like an AGP. You might look to see if you have an empty AGP slot, then you would just have to get a new vid card, which is relatively cheap compared to getting a new computer.
Don't know if you have an AGP? Just go to dell.com and put in your service tag number. That should give you access to the specs page for that machine. I had to do that when I was looking for RAM to see what was the fastest type my moboard could run.
Don't want to mess with it and want a new puter? Dell just bought Alienware.
