I wrote a guide for converting e200Rs into e200s, which can be found at http://chrisjs.com/?page_id=57. For those that want Rockbox on their e200R's, I made a bash script to help automate the process to some degree. The only non automated part is putting the Sansa into Manufacturing mode, copying files to it, and unmounting it. If you have any questions on using it, leave a comment. Also, there's an article on the Rockbox Wiki on installing Rockbox on the e200R (http://www.rockbox.org/twiki/bin/view/Main/SansaE200RInstallation).

WARNING: Before doing ANY of these steps, read the FULL instructions first. My bash script can't be stopped (with the exception of CTRL+C) so please be careful while using it. What it does is the same process as described in the Wiki article, just automated, meaning you should still read the wiki article, even if you plan on using the script.

Bash script to help get Rockbox on E200Rs

Short howto on using: Download the file to your home directory, run "chmod +x rockbox.sh" from the Terminal (Applications, Accessories, Terminal on Ubuntu) and run "sudo bash rockbox.sh" (or however else your distro allows you to run it via root)