Try MacTheRipper or DVDBackup for transferring DVDs to your hard-drive. Alternatively, check out HandBrake, which can convert DVDs to mp4 format and therefore conserves space. A 90min film usually takes up around 1GB in mp4, compared with just over 7GB for the average (dual-layer) DVD. Be forewarned that HandBrake doesn't include subtitle support yet.
All of these apps can be found at versiontracker.com.