I did get it working with Windows NT a LONG time ago. I'll be damned if I can remember how I did it, but I know I used Routing and Remote Access Services (RRAS.) This is available in XP/Vista/7 and it can be configured for remote access. Worth a shot, I guess.
I did it long ago by modifying this:
http://bwinton.latte.ca/Palm/ppp.htmlbut can't remember the details. its probably better to use Linux.
also, I had managed to find some sort of Internet hub/switch that has RS232 ports and Ethernet too. it was meant to be used the other way (sharing Internet modem connection to computers on LAN) but can work this way too.
