I linked to Apple's explanatory page for an Archive and Install back in post #12. You might want to read that for a full explanation. Briefly, everything in /System is replaced. Apps should continue to work fine. Your user and settings should all be fine. If something necessary was in the old /System, it is archived in a folder called Previous Systems, so you can retrieve it after an Archive and Install.

Good luck!

Trevor

Note though that if the issue with Entourage is due to some setting or preference thats wrong that too will be transfered when you do an archive and install. At least you could at that point pretty much flush the user account and recuperate all piece by piece from the archive that gets created at the same time.

Thanks guys ill look into this and keep this updated.