Just thought I'd mention that I am using *very* cheap cables in my (non-3D) HT without issues. The last lot I bought was 2x 1m HDMI cables for �6.99 delivered in 2008.
I think that the fact that *every* HDMI device in my HT is connected to my Lumagen Radiance makes a big difference.
Why?
Well, reading the Lumagen support forums, it's clear that although HDMI cables carry digital data, the HDMI interface specification is too loose and difference in voltages at either end of the cable can cause problems. If both ends of the HDMI connection are at the opposite and extreme end of the voltage specification, things just don't work. I think it's likely that the Radiance (which is designed to work with everything and is extremely well engineered) is an excellent buffering hub.
I run:
SkyHD -> Radiance
Oppo -> Radiance
HDDVD -> Radiance
PS3 -> Radiance
Radiance -> HD621
Radiance -> projector