Personally I do not recommend RAS for dial in if over 4 or 5 lines. For
less then the price of a qualty computer that can handle the load you can
pick up a used Lucent/Livingston PortMaster 2 or 25. It would do a much
better job, be able to handle more ports, allow lings like packet filters,
RIP, OPFS, Subnet routing, much better accounting. You can even use NT's
users database for passwords and user names if you use their RadiusNT (Free)
and AFAIK IEA's RadiusNT also supports it. IF you want to be able to offer
both ISDN and 56K access then you can get a PM3. A more expensice route but
no external modem headaches.
Just my $.02 worth.