Id say unless you have the best equipment and knowledge, to avoid it altogether. My boyf got into it at college and got thru so many blank dvds it cost him a fortune. most just got slow and jumped at the ends, but alot of them had the sound out of sync. if you do it, copy from one dvd straight to a blank- if you take it off the net, get expert advice first.
My advice is to avoid it, cos its costly and time consuming. Just buy the dvd from a cheapo site!