I recently bought a u3 SanDisk micro cruzer thumb drive. Payed way too much for it but it was in the name of testing a technology I have wanted to compare to portableapps. The end result is if you ever get a u3 thumb drive remove the u3 section and install portable apps.  My reasons are as follows:

1.  Portable apps is free and so are all applications that are developed for the thumbdrive platform.
2. SanDisk them self have realized the flaw for the u3 drives and have actually joint with microsoft to developed a new platform.
3. U3 applications just up and die on you sometimes. Trillian was the first to go and i cannot uninstall the application. I would like to try a force delete however I’m pondering the fact that the space maybe lost into the voide of nothing-ness and i would not be able to recover that 12mb unless i perform a full fdisk on the drive.
4. U3 does not work with any other operating system other than windows xp (not all of them i think there are problems with some service pack patched machines)
5. Portable apps application library is expanding at a very tolerable rate.

As of today i will format my u3 drive and install portable apps and take it from there. I hope there is a version of pidgin for portable apps soon. If you need to remove your u3 setup you may use this tool provided by u3 for removal of the smart part of your thumb drive (point and laughs at u3)