I have a notebook that spends about half its time in the office. I go on business trips with it, but don't carry it back and forth to home.

For my Outlook mail and contacts, I just leave everything on the server and use offline synchronization to "make copies" of everything for local use on my notebooks. This keeps everything in sync.

I use Briefcase or it's XP incarnation, "Offline Files" a moderate amount. I have to admit that I don't have many files that I access constantly, so I'm not a heavy offline files user.

As an alternative, I've used the Unison file synchronizer to sync up big directories across offices.