http://support.dell.com/support/edoc....htm#wp1043338
is the link to the service manual for your system. Unfortunately, you have only 1x pci-e lane expansion port. You do have available pci slots, so something like
this card from tiger direct would be what you would looking for to reach minimum specs. (EG. just able to run it, and probably at low resolution)
At this point, you should ask yourself how important it is to run those programs well, and to find what the lowest minimal graphics eye candy you can live without, as anything more will cost. (depends on how much you want to spend) considering a student budget, the
Econobox specifications from the techreport should provide a good basis for a system that won't have to be replaced for 2-5 years.
Or, you could probably find some decent gear from the last ~2 years that's been used, but is now obsolete, by those folks who are spinning those upgrade wheels.