The ni500 has one shortfall, not very good at extreme distance from the
exchange, if distance is borderline go up to the M1122 four port.
Basically you're done.
If your users are wincentric using M$ ICS protocols are excellent (and I
NEVER thought I'd say anything good about M$). I have three business
clients running ICS.
You MUST install ICS correctly and the wizard isn't too good, email me
if you want to go this way. ICS takes care of netbios name service
tranparently also...
Otherwise the linux answers you will get will be fine, Smoothwall looks
excellent.
Adrian