I have seen the:
Shuttle Barebone SA76SG2 AM2 2DDRII PCIE S/V/L SATA
Shuttle AM2 GeForce 8200 PCI-E Black
at DABS (UK) but not sure that Ubuntu server will install on these.

We do not need gaming or graphics so what would be the most suitable platform and if not a shuttle (fits nicely on a shelf in the office) what should I go for?

Has anyone got Ubuntu server running on a shuttle and if so which model and spec.?