Sandeep is correct. For workstations to work with SBS properly they must be one of the following:

Windows XP Professional
Windows Vista Professional
Windows Vista Enterprise
Windows Vista Ultimate
Windows 7 Professional
Windows 7 Enterprise
Windows 7 Ultimate
Windows 8 Pro
Windows 8 Enterprise

Keep in mind you are limited to 5 PC's. You should visit the FAQ for more details here:

https://windowsupgradeoffer.com/en-US/Home/ProgramInfo

JamesNT

James Summerlin
My personal site: http://www.dataintegrationsolutions.net
james@dataintegrationsolutions.net