I don't really know about converting them with Nero- I never managed to get it to work for me anyway......
I use this to copy DVD's tho - got it from a link in this forum - superb programme!


http://www.dvdshrink.org/
Rip em and compress em to fit on DVD-R's using that programme, then just copy em to a DVD-R using Nero...... Bout an hour to rip a disc, and about 14/15mins to burn...