Handbrake on a mac needs VLC to handle the decryption (ripping) – the PC version doesn’t decrypt at all, so you need a separate ripping program.
Once it’s ripped, just run it on the iPad default setting in Handbrake. This will encode it to an ipad/tunes compatible file type (m4v) and shrink the file from the 8GB DVD rip to about a gig, whilst giving you picture quality optimised for the iPad.
The benefit of running a separate ripping program, is that you can rip a few DVDs, then queue them up to encode in Handbrake overning (takes a while, depending on the goodness of your ‘puter)