LCD Projector Help

I've managed to build an LCD projector using a free monitor and a free overhead projector. The only problem I'm having is that the projector's light source isn't as wide as the LCD panel, and it cuts off an inch on either side of the display. The hardware's control panel lets me shrink the horizontal a little, but it's not enough. So, is there any way to make the desktop's resolution be lower than the viewable area of the screen? If I could do that, the entire display would fit perfectly into the screen. E.G. displaying an 800x600 desktop within a viewable screen area of 1024x768

Hey man ......I know it's kinda late, but I may have a solution to your cut-off video .... if you go to http://www.lumenlab.com/forums/ and do a search on "video stripping" or "lcd stripping" ... I have came across this issue before and there's some software out there that'll cut video to specified dimensions so it won't fill your whole lcd. Hope this helps you. Good luck!