TS Gateway?

From an external site, i want to Remote Desktop to a machine on the
workplace LAN.

i cannot VPN to the workplace because the the local router, like almost all
routers, cannot handle more than one Microsoft PPTP VPN connection. (Either
that or they just don't allow it - pick'em).


So what would be idea is a way to have Remote Desktop client software have
the ability to connect to a "proxy" or "gateway" computer that i can expose
to the Internets, and then that machine can forward the RDP traffic to the
desired machine on the local LAN. It would need to be on port 80 (HTTP), or
if really need be port 445 (HTTPS, with no valid certificate).


Spelunking through undocumented things, i see an option in the client
software: "Connect From Anywhere", where i can "configure Terminal Services
Gateway settings to connect to remote computers behind firewalls." Which
sounds like exactly what i want. But the going to my 2k3 server machine, and
going to Start->Help->"TS Gateway" yields no mention of any such technology.

Does such a technology exist, and if so how do i enable it on a server, and
where in the help files in the documentation for it?


.