depends what you wanna us eit for.
If its just to share connection over LAN then you just need a bog standard box to run Smoothwall on, i dunno much bout that thou, never used it
IF u wanna run ftp servers and actually use it for summet good aswell, then depending on what OS u wanna slap on, ull need a better spec.
NT4 can run quite happily on a 400mhz cpu + 128 if its just light stuff
but if you have hundreds of users
(unlikly) then u need more cpu stuff.
I run my server on (see sig) and it runs fine. I run FTP, MS Proxy, Shoutcast etc etc. All works fine and dandy
If u use Win2k Pro/Server then just use the internet connection sharing software on there, that works fine
- if u wanna go bit more technical then use summet else, like MSProxy
which is good
As for your connection - i think u shud be able to get it to redial when disconnected
HTH