I'm not sure what some of the other people who posted here were doing with their copies of IMSafe that caused problems for them, but it does exactly what I need it to do without crashing, causing any problems, or having any issues with permissions. I use it now to sync a frequently-used folder between my Powerbook, .mac account (iDisk), and desktop. Works flawlessly, updating only the files that have changes to keep my computers synced without having to connect them. Extremely easy to use and seems stable (although keep in mind it's a beta). So far I'm very pleased and highly recommend the program, espcially for synching files/folders.