Windows 7: Disallows 1024x768 for TV, but 640x480 has way too much overscan

Here's my problem, if I select any resolution but 640x480 and open Windows Media Center, Windows 7 will automatically change my resolution to 848x400. Even if I alt-tab out and then change it back to 1024x768 (only in ATI CCC, Windows 7's desktop resolution Window won't change it, even though it's selectable) if I click on WMC again it will adjust itself back to 848x400.

I don't mind using 640x480, except that it has crazy overscan, at least 10%, cutting off subtitles and the like. ATI's CCC can't compensate enough for it.

So I need a way to force (and keep, no matter what app I open) 1024x768 in Windows 7, or a way to have full overscan control to compensate for 640x480.

Any thoughts? Thanks in advance for any ideas!

Syspecs:
CPU E6750 @ 3.2gHz
Mobo: P45-UD3R Gigabyte
Vid: ATI Radeon 4870 1GB
OS: Windows 7 x64



Edit: I should note, Vista allows me to select, and keep, the 1024x768 resolution when using WMC.