, I moved your post to this existing thread. As indicated in post 1 of this thread, the signal must be unencrypted for HDMI to be used (with an HD camera for example). Most signals from service providers are encrypted and require you to use component video. Component Video cables can handle signals up to 1080P, however, there are sometimes restrictions in the STB, but usually 1080i is possible.
Here's the FAQ on Recording HD:
And here's a post useful for those new to the forum - FAQs, Search Tips, Optimization, etc: