Neteui and Windows 7

I currently have a small Windows network consisting of 2 PC's running
Windows SP Pro. I am separated from the Internet by a Linksys router. The
Windows file system is bound to Netbeui to give an extra level of security
as netbeui is not routable. I understand that Netbeui is not supported by
Microsoft on Windows XP machines. However it appears to work perfectly.
I want to add a third PC running Windows 7 to the Network. Is there a
version of Netbeui, either supported or not suported, that will run under
Windows 7?
....thanks