DivX is a godsend for anyone who travels a lot and watches movies on a laptop or other portable device that supports the format. What it allows you to do is compress DVD movies down to a fraction of their size without sacrificing quality.
Traveling with the actual discs means I have to bring my laptop’s DVD drive and, as a result, I cannot use the modular bay for the 2nd battery instead. Without the 2nd battery, the laptop only lasts about 3 hours (vs. 5 hours) and most of my flights are over 3 hours long nowadays.
It does take some extreme nerd cred (and about 6 hours of computer processing time per 2-hour movie) to get the best quality vs. compression but the ability to take a dozen movies with me at under 1GB each makes the ordeal worthwhile. For comparison, a 2-hour uncompressed DVD movie uses about 4.7GB. The DivX format allows me to take 5x as many movies compared to just ripping the DVDs to my laptop’s hard drive.
If you are interested in earning your nerd cred, grab the DivX Community Codec (free) and read up on Gordian Knot (free). Otherwise, just buy DivX Pro for Windows ($20) and include the MPEG-2/DVD plug-in ($10) which together will provide everything you need in a simple-to-use interface.