Well, Dells are based on PC architecture too, which means they use the same voltages (+12v, +5v, +3.3v, and -12v.) as a standard ATX system, although the pinouts may be slightly different. An easier way would be to get an adapter like http://www.endpcnoise.com/cgi-bin/e/std/sku=dellconverter or cut and splice the wires, as there are pinouts for Dell and standard connectors available everywhere on the Internet and all you need to do is match the voltages.