Hi there,
I found a solution for this. It's the "Aspect Ratio" setting in the Intel
driver. Unfortunately, in Windows 7 the Intel Graphics Settings tool is missing, so you cannot choose between "Maintain Aspect Ratio", "Center Desktop", "Stretch to Full Screen"...
The default seems to center the desktop. I now found the registry setting for this.
Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video\{CLSID-here-you-have-to-find-the-right-one}\0000\
In this key, you find many entries, beginning with ~3DMark03.exe and several other game executables.
Now search for the DWORD ForceBorderForMAR. Set it to 1. This worked for me and stretches non-native resolutions to full screen.
Hope this helps...