When IIS (for SSL) and Surfer run on the same box, what
as port assignments do you all recommend since these both 
use 80 by default?

I vaguely recall something about using virtual IPs (i.e.
two IPs on one physical box), but am not sure about how
to set this up.

Even though the SSL port is not the same as Surfer's 
port, MMC and IIS both complain about the conflicting
port 80.

If IIS is only used for SSL, it probably makes sense to move it to another port for HTTP, such as 82 & 83 (HTTP and ADMIN).

The virtual IP address is also not a bad option, since it provides some simplicity for users should IIS do some double-duty as a web server.

To setup a virtual IP address, you first configure your LAN card so that it supports more than one IP address (network settings, adapter, advanced).

Then, you tell IIS to listen on one of the IP machine addresses and tell Screensurfer to listen on the other. Screensurfer is configured for this using the registry setting ListenIPAddress-- change it to the nnn.nnn.nnn.nnn setting matching the IP address that IIS is not listening to.