Cable TV High Definition converter

My brother in law told me today (I am a newbie to home theater) that if I have cable (Comcast) the HDTV signal being sent over the cable is being compressed and that there is a box I can buy that decompresses it so that I get true (or at least better) HDTV. Is this true? If so, what is this box called? What brands are there? Is any one of them better than another?

As far as I know, Comcast provides HD in some areas for some channels. You need a digital HD box, a component video cable, and an HD monitor (display) to view it. In my area, the Comcast rep said they are providing the Motorola 5100 HD cable box. If you want to know the skinny on this, check with the video geeks (we are the audio geeks) at
I have also heard the compression comment. I use a cox cable converter (I think Motorola) for DiscoveryHD, ESPNHD, HBOHD, INHD1 & INHD2 and a Zenith OTA receiver for the networks and can not really tell the difference. In fact, it appears to me to be driven more by content quality than anything else I can see. Some of the geographic stuff on DiscoveryHD is breathtaking while yesterday's NFL playoff game on ABC was just good. PBS over the air has some high quality stuff and HBO's movies can be soft. WRT the latter, my understanding is that that relates to the studios being nervous about the potential for bootlegging high quality digital movies. The same rationale for holding back on HD-DVD's.
I am a novice at HDTV, but I understand that the FCC has only recently set the final standards for cable and satelite transmission interfaces and the industry is only now starting to get their act together. I would be cautious until this fall.
I have had the Motorola 5100 for 6 months now. I have not noticed the need to add additional processing to the HD signal. It is excellent. The HD signal might be compressed, but movies on HBO in HD are equal to, or better than, viewing them on DVD. I would get the 5100 and judge for yourself.
Equal to or better than DVD? They better be better than DVD, 1080 vs 480 lines!
I have the Arcam 27 as a dvd player and you bet; some HBO /SHO movies have less pq. This applies to much of the local ota content as well.(i.e. the Rose Bowl game). Still much "hd" content is shown in 4.3. However "good-hd" content is no match for the best dvd. AND, the reverse is true for the audio.