looking at your picture #4, you have a video card installed in this computer. It also has 2 ports... if you are plugging into one of these, plug into the other one and see if it sends signal to your monitor.
if that doesn't work, with the power cable removed from the computer, and yourself properly grounded, remove the video card and replace it with the spare vid card you said that you have. you might want to be sure you have drivers for both of these cards as this may still be just a driver issue as 123 runner was saying.
FYI: if you are curious about what your pictures are:
2: @left, gray box: power supply. @center, with silver fins: heatsink for the processor (processor underneath) don't remove the heatsink, unless you know what you are doing. @just above the heatsink, RAM slots (Looks like all four are full) @right, AGP & PCI Slots
3: @left, CDROM/CDRW/DVDROM/DVDRW Drive (Depending on model of Dell computer you have. @top center, looks like probably a 3.5" floppy disk drive @top left, Hard Drive (looks like you have an extra slot for another hard drive if you want.)
4: Back panel showing input/outputs for: parallel printer, 2 com ports, ps/2 mouse and keyboard, Network port, 2 USB ports, and audio (pink:microphone, green:line-out, blue:line-in) in addition to your two ports for a monitor.
5: AGP & PCI slots @left black fins: northbridge heatsink
6: Processor Heatsink, Northbridge heatsink and RAM slots @top
Edited by jester620, 24 September 2007 - 11:45 AM.