This have been my intention, but the filesharing is becoming more and more frustrating with google. I've looked at third-party solutions to the missing webdav/drivemapping part of google docs but it doesnt seem good enough.

Also, I'll miss out on security policies which can be nice. As it looks now, we will go with a minimum active directory machine handling local filesharing and logins and gpos.

I hope I'll be able to keep away from sharepoint and exchange, but i'll just wait and see.