QUOTE(Zero-Cool @ May 5 2006, 04:08 PM)

What could be wrong?
Hey, OPA!
1. Your Xbox uses PAL.
2. The cable you bought is a crappy 3rd-party cable.
QUOTE(diddler1979 @ May 5 2006, 04:35 PM)

Almost certainly its because you are using a PAL xbox. It needs to be modded to NTSC for the HD options to become available.
How can you make that conclusion from the given information? 
I have seen more people who bought a cheap 'HD'-cable compared to people who did not read that you need an NTSC box for it.
And the Xbox only needs to be modded temporarily. You can even go on Live again, provided that you only change the video output from/to PAL/NTSC and not anything else.