FairUse Wizard is an open source (GPL) DVD backup tool. It can directly encode fron DVD (without ripping) to XVID/H264(video)-AC3/MP3/Vorbis(audio)-AVI/OGM/MKV(container).
It also has internal codecs (doesn't need VFW sh*t).
It would be great to have a portable version...
http://www.fairusewizard.com - Official website
http://www.fairusewizard.com/Release/fu-src.zip - source code