No 1080p support on 2 year old Toshiba Satellite Pro?

This as been bugging me for a while.
I've got a Toshiba Satellite Pro A200 with Intel Integrated GMA900 graphics. The specs say it can drive up to 2040xsomething displays over VGA, but it flat out refused to drive my 1080p display (1920x1080). I tried everything I could think of, from editing the driver INF file to list the mode as standard, to editing an INF for the monitor, in case the EFI information wasn't being transmitted propperly. No joy. Highest I could get was 1680x1050. Anything above that just "scrolled around" inside 1680x1050px to show the rest of the desktop.
The monitor works fine at 1920x1080 on my Macbook btw.
Argh! This has been driving me crazy for a long time!
Anyone else have a similar problem?

Yep. Sure about the specs. When I say "scroll around" I mean the actual size of the desktop was 1920x1080 but only 1680x1050 was visible on the screen. When I moved the mouse to the edge of the screen, the whole display shifted position to reveal the rest of the desktop, like when you scroll around a window. ...if that makes any sense :-)