You can do HD without HDMI (DVI, component etc are all HD-capable) but LilJen is correct, Sky have never made a HD box without HDMI (in fact come to think about it, I am sure they disabled the component HD viewing a couple of years back on the early boxes thanks to a lack HDCP support when using it).
As for 80GB... sound suspiciously like a Sky+ PVR3 box. Aka, non-HD.