Ok, well I've been having problems with my graphics card but 2 days ago my computer crashed while watching a movie on vlc (wasn't the first time: happens fairly often; I can watch on average 50 minutes or so before it decides to crash) but when I restarted the resolution was 640x480 with 4 bit colour. I can't increase it to more than 800x600 with 4 bit colour and if I start it up on VGA mode it comes up as 800x600 with 16 bit colour. I have a V203H Acer monitor which has the capacity to go up to 1600x900, which I had prior to the crash.
Now second problem:
If my computer goes to screensaver, I can't get the video to start working again. If I move the mouse or press a button, the screen flickers between a couple shades twice or so then a dialog box saying "input not supported" comes up. My computer specifications are here: http://www.tomshardware.com/forum/306250-33-graphics-card-crap-comp
EDIT: I can't see the sub-section headings on the forum so I don't know where to post this and I just posted it in graphics. Can a mod please move this to the right sub-section?
What cable are you using to connect between the monitor and GPU?
Im assuming the basics are good - connectors checked, plugs reseated and so on, so that leaves psu or card. The card is definitely old, but it souds like the psu could be bad also.
Remove and reinstall your drivers. Hopefully you kept the ones you installed. I dont like changing versions when Im debugging stuff.
I would swap components between other PC's to see if you can identify a bad card if the driver update didnt work.