I've been using DVD Catalyst 3 from tools4movies.com for a long while - originally for my netbook, and with my N900 for the last few months. They have a very good free version (DVD Catalyst Free, referred to as a trial, but has no restrictions) and a $10 version that adds more tools, editing functions, and additional presets, including two for the N900. It's easy to use and has worked great for me in Windows XP. Some DVD's have stronger protection that won't convert (I've run across just two so far), but the upgrade has a free available plug-in to help on those.