Mark,
Servers require a couple of things initially, the right hardware and the right OS for your application. You can easily make a server using a 200mhz Pentium S system with 64 meg RAM and a 2 geg drive running NT4 and that will support HTTP, FTP, a proxy and firewall. But, the system will obviously slow down as hit rates rise because you will have 80meg physical memory load and the processor will have a hard time jumping back and forth between VM and PM. As hits increase you move the HTTP and FTP services onto another server.
A good starting size for a server is around a 450 mhz PII with at least 128 mbytes of RAM. The more RAM you have the better the server will perform as it gets loaded with services and external users. If you can afford to get adventurous and it's a professional setup you want, then the minimum should be something like a dual 450 PII with 256 to 512 mbytes of RAM.
Storage size (after you take care of the OS, VM and their support services) doesn't mean a lot. Unless you are planning to run a large FTP site, become a UseNet carrier, e-mail service or provide webpages for external users.
The more services you supply, the more servers you need. As an example try to use one server for every 1 to 2 server daemons (Server A: Proxy, Firewall, Http. Server B: e-mail, chat. Server C: FTP. etc.) If you use the right proxy software, you can run most of your server daemons behind the firewall, just make sure you have good security and that the server daemons are stable.
Meckanic
