LG TV Setup Help!

I have a very annoying problem, and I hope you guys can help.

I have a LG 32' TV. Up until now, I hooked it up with a VGA to VGA cord, and everything worked fine. The problem started when I wanted to use a DVI to HDMI cord.

When connected via VGA, the TV is configured to user XGA mode (max is 1366 x 768, but I have it setup at 1360 x 768).
When connected via DVI - HDMI, the image seems to go farther than the screen, however I don't experience screen panning... the image is just "bigger" than the surface on my TV. I dabbled in ATI Catalyst Control Center and attempted to use "custom" HD resolutions... either I suffer from the same problem or I get the opposite problem (the image is too small, and there is an unusable black border around it).

I also have my Xbox 360 connected to this TV, via HD Composite, and in the settings it is set to use 1080i - everything works properly, and I can see the entire image.

Since the 360 works fine, I deducted that I can somehow make my PC work fine with that resolution also. Is this even possible? And if it, what am I doing wrong?

Your help is really appreciated, and thanks in advance!