I have two of the model Carl suggested here, one in the family room system because of satellite DVR, one in the master because of TIVO HD box.... they don't hurt the picture quality.... of course I also have a dedicated 20A line with JPS labs romex going to each spot... so that doesn't hurt things either... But these have served me well so far...
I do like APC units as well... either way, it's nice not having the TV go out for the repeated dips that happen a LOT around here, especially in the summer. I got nearly 30 minutes viewing of the 60 inch plasma and DVR on battery power before it ran out last time there was an extended power outage... better than sitting in the dark for that 30 minutes...