HD picture quality could range from good to spectacular, depending on the quality of the screen. regular SD will probably be mediocre to good at best, since (as anyone who has used an LCD can tell you), these displays are not good at showing a non-native resolution. If you don't absolutely need an LCD, i might suggest a tube-TV. for less money you can get a 32" 4:3 or 30" 16:9 HDTV. sure, they're heavy as hell and take up a lot of space, but they still have an outstanding picture.
The only way to tell for sure if you like the quality is to see it in person. ask your friend to demo one for you.
edit: as far as tuners, you'll need either an over-the-air (OTA/terrestrial) receiver and an antenna to decode broadcast HD channels (ABC, NBC, CBS, PBS). If your cable company offers HD, then you can get one of those instead to get your premium channels in HD, too. Comcast is actually quite reasonable with HD (just about the only thing that's reasonable about them) and gives you an HD box for free and any HD channels that you already pay for. (so, if you already have the showtime package, you get the showtime HD channel for free). Comcast also has an HD DVR in many areas for $10/month.