Personally I use VirtualDub, but it does take some setting up. I've found it to be much superior to AutoGK but like I said, it does take some tweaking to get the best results.
As far as codec's go, I'd have to say agree and say that Xvid is the best to go for as it is free. The only problems I've had with Xvid are trying to figure out which version is the latest as there are a few people who develop it.
The original Divx 3.11 is no longer under development Project Mayo, but DivX development continues with Divx 4, 5 and now v6.
Version 6 of DivX has support for Hi-res and there are now a number of DVD players that will play DivX content direct from cd or dvd.
My fav best decrypter is CLADDVD. Its very fast and has lots of options for choosing which parts of the dvd you actually want.
More info on all aspects of ripping can be found on Digital Digest.
Bit of a rant, sorry got carried away.