You have just described our system in your wish list. Just I`m never quite sure we have quite got Utopia. 10 computers now linked to a server that uses Winproxy to connect to the internet via ADSL. Winproxy (Up to 10 user license) handles each individuals e-mail address and delivers mail to everyone. It also allows you to keep track of Internet use if you`re bothered.
Getting everyone to store company data to the server is a bit of a nightmare - people still want their own private copies stored locally. Suggest you add a removable storage device for daily backups and alternate 2 devices. Maxtor do some good 40Gb ones.
Finally if you don`t have the expertise in house get someone to fully spec it and commission it.