Far too many people are asking me the same question over and over despite it being in the manual.

There is NO overscan fix support for v1.6 (Xcalibur) Xboxes

There isn't likely to ever be a fix for it as the chip is largely proprietary (though its based on the Focus chip). Until we (xbox-linux) can get documentation for the chip or somehow perform a miracle, it will not be fixed.

A rather horrible solution (which is what modchip makers use for their built in OSes - it works well for these because the screen layout isn't as dynamic as Linux) is to make move everything closer to the center of the screen. So if you are using an application, shrink it to fit your screen.