They should be able to see the shares and depending on the age of the Mac, they should also be able to login to the domain to access the shares. Try disabling SMB 2.0 on the SBS 2008 server.
SMB 2.0 was introduced with 2008/Vista. It introduced several features that's created connectivity problems.
http://technet.microsoft.com/en-us/library/bb726965.aspxIt's not uncommon to disable advanced features (new features) when they create connectivity problems with other devices.