Picture quality is measured in "scan lines" or "lines of resolution". The more lines you have the better your picture looks.

Everyone's racing to catch up with Blu-ray Disc's superior signal. Up-converting DVD players get close and some satellite providers are offering on-demand 1080p movies, but neither are quite as clear as Blu-ray Disc.

Full 1080p HDTVs are king right now. Some even offer 120 fps (frames per second) or "120Hz" as they're sometimes called. Ask to see one of these "120Hz" 1080p televisions in action at your local electonics store.

If you've purchased an HDTV several years ago and are being told that you can't enjoy Blu-ray Disc or 1080p signals don't worry about it. 1080p sources which have been down-converted into 1080i signals are nothing to complain about.

If you're holding on to your old analog set because it's paid for and it still works you won't be left behind. All HD signals from all HD equipment can be output at a picture quality which is compatible with your old TV and rivals your DVD collection.

Here are some links which might answer some of your other questions

HDTV Truths

Blu-ray Disc