The maximum resolution I can select for my screen, using windows control panel/games is 1280 x 1024, but when I ran 3Dmark06 tonight, in the log file created it lists my screens' maximum resolution as 1600x1200. Could this be because I don't have the right driver? The control panel simply sees the screen as a 'plug and play monitor' with no other details. As for which screen it actually is, I don't know. It came with the PC I bought an there is no manufacturer name/model on it. It is connected through D-Sub, through a Radeon 9550.
 
Oh, and just in case you want to know, my 3D score was 568 ! But I only did it so I can see how this beast stands up to my new rig, which thankfully, is almost ready.
 
Thanks for any help!

I'm guessing you have a 17inch non-widescreen LCD hooked up to it. If that's the case, almost all 17inch non-widescreen monitors use a resolution of 1280x1024.

It would appear to be a 17", and it's definitely not widescreen. Thanks for the quick response.