After much testing of various products, and trying to understand the iPad video file format ( H264 codec, AAC audio, and mpeg4 video format), I have found 2 products that work very well for me. The main criteria in selecting the software was quality of the picture on the iPad, and speed of conversion, and the ability to include subtitles.
To run a DVD movie, I use Magic DVD Ripper 6.0, and select iPad output profile. It generates an mp4 file for the iPad. It rips the DVD quickly.
To view avi, mkv, mp4 ( not all mp4 files are compatible with iPad2) and other video file formats that I may have, I convert any these to an iPad compatible file using Xilisoft Video Converter Ultimate 7. It too is very quick, using the CUDA GPU acceleration facility on my motherboard. Select output profile iPad2 -H.264 HD video (Don't use Ver 6, there are too many bugs e.g., background sound is present, but speech is not, on some mkv file conversions).
To load the resulting mp4 video file from the computer to the iPad2, connect the iPad to the computer with the USB cable, open iTunes, and make sure that your iPad is shown in the LH column under DEVICES.
Select movies in the Library folder (found in the LH column), then go to File> "Add file to Library" and then find the newly created mp4 file on your desktop. This will then import the movie file to the Library Movies folder . Next step is simply to drag and drop your movie file in the Movies Library to your iPad in the DEVICE folder. Watch the top of the screen to see the barline indicating progress on the transfer. QED
To delete a movie file in iPad2, either delete it using iTunes >Device> select the file and press the Del key on your keyboard, or go to the Video section on your iPad2, press and hold the movie file icon you want to delete until the small X appears at the top of the file icon, press the X, and the movie is deleted.
I have also found that the latest DVDFab 18.104.22.168 will convert a DVD to iPad video file format quickly using the CUDA acceleration, but the resulting video was so broken up as to be uselelss
hope this helps,
PJ ( Australia)