We've had good luck with Cyclades PCI serial cards. Each 2 logins through
RAS costs us about 1% of CPU. When we were maxed out with 32 users active
we showed 15% CPU usage. Good cards, good drivers, worked for us. I think
you can put two of these cards supporting 32 serial ports on each card in
one machine, for a total of 64 ports.
Having said that I think it's only fair to mention that we are in the
process of switching over to a Livingston Portmaster 3 and RADIUS, for 56k
dial up and port density, but the Cyclades sure did the trick for us when
we were first starting up.
David Glynn "When you're swimming in the creek
dglynn@mathware.com And an eel bites your cheek
That's a Moray!" - The Freak Bros.