I hear there is free software you can use, but the stuff I found I didn't like, so went ahead and paid for a product that has been working fine since last Christmas. I have IMTOO DVD to iPod converter and use it to copy DVD's I rent from NetFlix in 320x240 (small filze size) and 640x480 (for viewing on TV), either can be run on the iPod. It also can copy in other formats.
I burn each movie in both so I can have the smaller file on the iPod but have the bigger file for better viewing on the TV, if the movie sucks I'll delete the big file but (maybe) keep the smaller one for future viewing. The small file is usually about 470meg and the big ones can be almost 2gig. Any more than 2gig and iTunes doesn't seem to want to deal with it.
After using the IMTOO software I just import the movie in to iTunes, then push whichever program I want to the iPod.
I also have another program from them to convert mpeg to iPod, which I use for when I send Tivo recordings to the Media Center PC. I use Media Center to record the TV program, a shareware to convert it to mpeg, then the IMTOO software to convert to something iTunes likes.
I don't recall what I paid, but has been well worth it, we don't even bother to watch DVD's we rent, just copy them then watch sometime later when we want.
http://www.imtoo.com/dvd-to-ipod-converter.html