For most of our systems we build the server ourselves using off the shelf components.  Most of the hardware is similar to that of the workstations we build with the exception of the mainboard (which is a higher grade) and the Hard Drives, which are usually specifically RAID edition SATA drives in the servers.

We do not have a specific brand of pre built machines that we would recommend over another, but any major brand server should be capable of acting as a server for a small Myriad network.

I can't see a problem with the Acer machines, so long as they have enough expansion slots for all the cards you need to add to the system.  The spec I found on the web for the Power FG only had 256MB RAM so I would recommend upgrading to 512MB if that is the spec you have.

You can use the server as a gateway if you like as it should not cause a problem.  However, if you already have a modem/router and a small network, then you could just add all of the machines on to the router and let that act as the gateway.  Doing it this way would make it slightly easier to achieve things like remote control of the studio machines.  On the other hand it would make remote control of the studio machines easier.

Hope that helps.

You could do - in general the drivers for Windows XP are the same as for Windows Server 2003, so you shouldn't have any hardware problems.

It wouldn't give you any real benefits though as you would still be limited by XP's inherent design.

That said, for a small network you may get away with it