One of my home computers recently stopped displaying anything on the monitor. From the description that was given to me by the person who was around the computer (as vague as it may be), he turned it on, walked away from 30 or so minutes, came back and saw a screen full of 0's. He didn't know what to do so he turned it off and turned it on, and when he did, it was not displayign anything. The copmuter still turns on, the fans all still run. I've checked to see if it's the monitor, but that wasn't the problem. I took the graphics card out of my other desktop and put it in the see if that would work, and it didn't display anything on the inserted graphics card or it's integrated graphics system. Any advice would be much appreciated

Sounds like a motherboard problem.
Any beeps?
Was it running on onboard video or a seperate graphics card? On some systems, you have to set the bios appropriately before switching between these or else you'll get no video.

I was afraid it might be a motherboard problem. No beeps, I've tried starting it without RAM and such, but nothing. It was running an integrated video, and I didn't put the graphics card from my other desktop into it until the problematic computer starting acting oddly.

At least one video card (and monitor?) known to be good, no beeps, doesn't sound good I'm afraid. As a "final" check, if you have another system you can try out the various components which might be interchangable to verify their seperate integrity.