Well you probably won't be able to run 2560x1600 with that card even though an x1300 should support dual-link dvi. I think i know what kind of adapter you're talking about. Does the plug kind of look like USB? Dell's site doesn't have a manual for that computer so I can't find any info about the motherboard other than it has PCIe x16 and x1 slots. Post the service tag so I can take a look at the specs (or PM it to me if you would rather not post it)
Something like this will work.
http://www.newegg.com/Product/Produc...82E16814161197