If yiou have an ATI card"
I had a similar problem with my HD 4850 when switching from vista to win7. I actually found a fix inside the ATI Catalyst Control Center. Open CCC and somewhere in the display configuration for your monitor ensure that there is no over/underscan. For some reason my CCC had a small degree of underscan turned on which led to the black bars you mentioned. A word of caution, when you start your games up and pick the native resolution the underscan may show up again. Just turn on any options for windowed mode and/or full screen and then turn off windowed mode again and the black bars should go away. Hope that helps!
Most all of us agree that an upgrade is not the route to take. It leaves useless files on your system and can cause conflicts.
Save all you Documents, Pictures, contacts, videos, music, etc to a flash drive,
Be aware, you will need to re-install your 3rd party applcations.