I had a silmilar need last summer for a small (2 person) firm when the 3 year on site warranty on their previous Dell server expired. The criteria I was looking for were:
- on site (next business day) hardware support for 3 years, so I don't have to sort out hardware failures
- tape backup so that they can create full backups simply (they have under 10GB of user data and it does not seem to grow much)
- identical twin disks for mirroring
I got them a Dell Poweredge SC430, but the SC440 appears to be the current product. I selected the Travan tape cartridge for backwards compatibility with the previous system but the price for tape backuip is a killer. Probably for the budget solution, I would add a contrib to backup to a workstation hard drive - since they have such enormous disks nowadays.
I configured the workstations to logon to the SME-Server domain, and run with My Documents mapped onto their user folder on the server, sharing an Ibay for their common files. Similarly mail uses IMAP on the server, and the local Outlook file was also moved to the server. This way, there are no important user files on the workstations. This means that there is little need to backup the workstations, as they can be rebuilt from recovery disks and the application software re-installed in the rare eventuality of disk failure.
Their domain user ids are registered on their workstations as Windows XP Power Users, not admin. I also registered the network admin ID on the workstations as amdin user, so that admin work on the workstation also has good access to the server and internet compared with a local workstation admin logon.