How to restrict Remote File access

Hi

I posted this to here because I believe that the solution is "General" Win
2003 Server configuration task.

My customer access remotely SBS 2003 R2 (files) recources via IPSec VPN
tunneled into PPTP tunnel. The company needs to limit the VPN File-Acces.
While a user is logged directly to LAN she/he can access more recources
(shared files) than when she/he is working remotely. The Remote mail is RDP
over HTTPS (it is working). Users don't have extra WSs to connect to. The
server houses one NIC and there is no ISA. The DHCP/DNS/WINS comes from the
SBS server.

I'm planning that the Remote users will log on to Domain remotely with their
standard Win Account using PPTP. So I propably need to establish some kind of
Remote Access Policy.

Further more, in the near future I perhaps need to implemet three different
Remote Access Policies. One for Local Sails Team, one for Local Managemet
Team and one for Offshore Remote Site.

I believe that NTFS rights is not the solution.

Is this possible to establish by Group Policies, how?

Can you please advice me?

Rgs,

Juha