PPTP VPNs can be established on Cisco PIXes as well as Microsoft RAS servers. Typically when the pptp connections are terminated on a Microsoft RAS server Richweb just needs to have the internal ip address of the RAS server. Richweb then NATs this server ip address to a public IP and passes tcp port 1723 and gre thru to the server.
If the Pix firewall itself will terminate the vpn sessions then there are 2 options for authentication:
1. local user database on the pix
2. pass thru authentication to a Windows Domain Controller
To use local accounts Richweb will require the list of usernames and passwords.
To use Windows authentication a radius server (part of win2k3) will need to be setup on the domain controller.