[Dustie]

Shrinked?... what exact procedure do you mean?... I don't think I've heard of 'compressing' DVDs or such...

.vob files are simply the DVD quality, which is high quality mpeg video.
.avi files are original DVD quality videos encoded/compressed using DivX/XviD codecs to reduce their file size without too much of noticeable image quality loss.

Difference between image quality of DVD video and DivX/XviD or such is usually always noticeable if you take a closer look at the image. You can make it almost barely distinguishable if you choose lower compression rate when converting DVD to AVI, but then the file size goes higher...