I have had a few people email me about overscan and underscan problems when they hooked their Revo up to their television. I would first make sure you screen resolution is set correctly depending on if your television is 720p or 1080p. You can do this simply by right clicking on your desktop and hitting "Screen resolution". If this does not solve your problem then you might want to check your television settings. All televisions are different, but on my Samsung under Picture Options I see the Size setting. I have mine set to Screen Fit, but play around with it to see if this fixes your issues. Lastly we can do some manual over/underscan adjustments via the Nvidia control panel.
Then hit the "Resize Desktop" button which will launch and application. You will see two sliders on your screen which you can adjust to fix any over/under scan issues. The green arrows should be pointing at the corners of your television.