Samba server & Win7

To put it simply, im looking for a windows 7 compatible samba server that has PDC/Kerberos support...(win7 does not support NT 4.0 based domain controllers)

im open to all ideas on a server platform =)
linux preferred or a mac app, but solaris is a viable option as well...

one note, my network setup does not run on Active Directory, i use Open Directory with kerberos

thanks
-NWT