I've been playing around with ripping and converting movies for the Bold over the last few days and have, I believe, figured out how to rip, properly encode and load movies to the device.
I have a mac and use MacTheRipper to rip and strip the DVD to my hard drive. I then use VisualHub to encode the file for the Bold. I also have figured out how to crop the letter box (on widescreen DVDs) so that you get full screen on the device.
Although I use the applications above there are many programs mentioned above and in other posts will allow you to tweak your settings. Trial and error is what led me to success.
I encode .mp4
Screen Size: 480x320 pixels
Frame Rate: 25 (I tried 30 and that works too, not sure if there's a noticeable difference)
Audio: 48,000hz at 192 bit rate
That's pretty much it. For cropping out the black lines of a wide screen (letter box) movie I use the cropping feature. I've found that if you crop 130 px off the top and the bottom that the movie fills the whole screen. VisualHub has a preview feature so that you can test your settings and see the result prior to encoding. You may have to play around with the cropping as I have found that not all wide screen movies are the same.
I found an interesting and helpful article here that got me started on cropping,
What's on HDTV?: Using VisualHub Advanced Options.
I've got 5 full length films on my 8GB card and the quality is amazing.
Good luck - Andrew