Uninstall your current graphics driver, then reboot into VGA mode, disable antivirus and install the latest driver. Reboot to complete.
You should also update XP to SP3 and apply the MS updates.
To see the temperatures and voltages under load, start
SpeedFan and leave it running on the desktop, then play a fullscreen game until it starts to slow down.
Alt-tab back to SpeedFan and take a screenshot (PrintScreen button on your keyboard). Paste the screenshot into Paint, save as a jpg and attach it to your next reply.
What's the name of the surveillance program you installed? Do you have a download link? Have you tried uninstalling it and running a virus scan?