SBS in my opinion is not really ideal as it has a number of background services that will interfere with FMS 11
Supported Windows OS are:
Windows Server 2003 SP2(Standard Edition)
Windows Server 2008 SP2 (Standard Edition)
Windows Server 2008 R2
and Windows 7 Professional
If you were thinking of SBS because it's a cheaper alternative to the other Server software then you might want to consider Windows 7 Professional as an option. Hope this helps.
I just wanted to make you aware that if you are planning on publishing your databases to the web now or in the future, you may run into issues if FileMaker Server is installed on a small business server. There is a conflict there as the same resources are being used so Sharepoint in small business server needs to be disabled.
This is not an issue if you are just hosting your databases via FileMaker Network Sharing.
Edited: added Sharepoint
Many thanks for your info, have had problems getting into the forum so theres been a bit of a delay.
I did post another question as we have been offered windows server 2008 foundation edition, there doesnt seem to be much difference, Hyper V is missing which wouldnt be a problem, i wondered if anyone had used this version yet