I have this strange tingly sensation at the moment. And it only ever goes off when illegal activity is being mentioned. The "sharing" of DVD's over the internet is illegal, as I'm sure the copyright warnings on your DVD's suggest. Unless of course you are refering to your own home made DVD's. And if that's the case, then my tingly sensation is just all wrong.
Just so you know, if you do rip your DVD home movies to your PC, you won't want them to be kept in DVD format, as they will take up alot of room. No sensible person would bother downloading a DVD from the internet. They'd rather download the homemovie in a different video format. For example DivX reduces the file sizes of movies by a dramatic amount (although some quality is lost).