"There are two ways to do video conversion from your DVD to a file for viewing on your PDA: direct from the DVD, or by ripping the DVD first and then converting the ripped file. I have found that the best bet is to rip the DVD first. This has two advantages: it saves wear and tear on your DVD drive, and it allows you to reconvert your video if you find it necessary."
Darius posted on the latest release of TCPMP last week, which as many people will tell you, is the best video player available for the Pocket PC. If you're relatively new to this application and were wondering about the best methods to rip your own DVDs for playback via TCPMP, check out the article. It's written with the Palm-based Zodiac used as an example, but the steps involved are virtually identical (just make note of your own device's screen resolution and you'll be fine).
This article has obviously not kept up with changes in the industry.
According to the site http://www.divx.com/divx/drdivx/, Dr DivX is no longer available and we will have to wait for an open source version to come available some time in the future. As an alternative you could use the freely available PocketDivXEncoder from http://divx.ppccool.com/.