VPN, NAT and LDAP or FTP

Hi, what do you think is the best solution for this? I read information about Super FreeS/WAN, CIPE, OpenVPN (vtun) and so on. But I cannot see if there is at all a possibility to have VPN between to NATed Intranets, each VPN GW situated behind the FWs - and providing the capability of FTP or LDAP traffic between the intranets. Or is M$ L2TP (with IPSec?!?) a solution to this. Or should we get a hardware solution (if at all this would help)? Please help me understanding all this :-/ Greetings, René