HTPC Image Not Centered on TV

[cmccrkn]

I have a HTPC I built on the cheap and I used a Radeon 7500 card hooked to a TV with S-video but I can't get the image in the center of the screen. I found the controls to adjust position but they don't move it far enough. It is off to the right and part of the computer desktop is clipped. Any suggestions for a HTPC wannabe?