Monitor static

[Coffee Break]

OK I'm currently trying to figure out whats wrong with my computer so here's the story. Yesterday morning I started up my computer and got these sort of scrambled spots all the way from start up until my desktop appears. When my desktop appears I usually get these huge bars of static basically. when I open and close windows there's usually large amounts of 'static' where the program either is or was, until it calms down and becomes less blurry. it seems to randomly get better/worse. yesterday it completely went away for a while but its been back ever since.

I hooked up my monitor to a laptop to see if it was just the monitor, but the monitor works fine. checked all of my drivers and they're up to date but I guess they could still be a problem. I've tried disabling and enabling my two video cards but had no success.

Here's my setup:
Dell XPS from about 2004, two video cards; DDR ATI Radeon 9800 xt 256MB, DDR ATI Radeon 9800 xt sec and I'm running Windows XP pro
I ran AVG virus scan and found 1 virus and 2 adware programs but I removed them with AVG and ran the scan twice more with AVG and once with norton and nothing else has appeared or reappeared. Nothings improved and I'm not sure what else to do.

Any information or help you could give would be really really appreciated. here is a screen shot of what the problem looks like:

[ThorXP]

Welcome to TSF....

This looks like you have a bad connection or intermittent connection somewhere more than likely inside the computer I would turn-off the computer and check inside for loose motherboard or the option cards may be loose possibly even something loose inside the power supply. When the computer is turned-on and you are getting this make like you are knocking on a door (Not too Hard) on the computer and see if this makes a difference in the screen resolution.

[Coffee Break]

I tried the knocking and it didn't change the resolution I checked most of the connections and they all seemed fine, but I can't get to the power supply area to check anything because its underneath the tower and I honestly have no idea how to get to it. any other suggestions? is it possible its a virus?

[sobeit]

are you running two monitors or just one? did you tried the monitor on both video cards? Open the case and remove the video cards, then reinsert one then plug in the monitor and see what happens.