My formats are AVI for space and Original DVD Files for quality.
For the people that like to store their media on the pc vs tons of shelving for dvd/cd's.
This question is more towards the DVD side of things. I just have CD's as MP3 files on the pc.
The reason I ask is because I am hoping to build an HTPC or at least store most if not all of my DVD collection on my pc. If I rip to an AVI file I can definitely save space but lose most of the quality. It is good for a flash drive though when you just want to take a few movies. If I rip as a backup, it takes up 3-8GB of space for the movie only (no features or menus) but I get the DVD quality and the surround sound it supports. Lately I have just been ripping a backup and AVI to have the best of both. Right now, the movies are played from the PC on a 54" rear projection (several yrs old but supports 720P and 1080P IF sent from PC ONLY) so if it is not a good quality AVI rip or dvd, the picture looks really bad.