And if you want to avoid the minor issues westfw referred to, you can edit the preferences.txt - the one in the "lib" folder
- for each IDE, and remove the comment mark before "settings.path=data". i.e.
# if you don't want settings to go into "application data" on windows
# and "library" on macosx, set this to the alternate location.
This will put your user preferences.txt in the "data" folder in each IDE.
(You may have to make the "data" folder and copy a preferences.txt into it.)
Doing this allows for wildly different Arduino IDEs on the same machine.