Excuse me if I don't make sense. I am half asleep.
I don't see why you would need a *server*. There is no need for this with your current setup, and I see it as a waste of money.
HOWEVER: If you slap a couple 200 gig hdd's in it, you can use it to store files. You could also use it to network all your computers to it the cenntral forr uhm all yours tuff like printers.
Considering you have a lot of computers, you could just say screw one computer and make it as the server. For example, it could have a large harddrive for sharing files, etc. Or it could as I said be the central for yor printers, etc. I did this kind of setup when I had Win2k3 but I trashed it becuase I dont have a need for it.
By the way, if you don't mind me asking, whatts the points of having so many computers? You a programmer or a lot of family members ^_~
Windows 7 Pro x64
AMD 965 Black Edition 3.4GHz
ASUS Crossfire III
Corsair 650 Watt
Sapphire ATI 5770
500GB Samsung*2 | 150GB VelicoRaptor 10K HDD
C# Programmer+Web Programmer