VPN trouble

I have a Windows 2003 server configured at a VPN+NAT server. It has two NICs, one with IP 192.168.0.1 connected to local LAN and the other has a static IP. I cannot connect from a remote XP machine using VPN, but local LAN comps can access internet. If I delete the NAT protocol, the VPN connection can be established, but local LAN machines cannot access internet. Ok, my server uses a dial up ADSL2 modem to connect to the net and so does my remote XP machine. Help !!!