I have 3 computers, all PC's, 2 desktops and 1 netbook. All are running either Windows XP or Windows 7. I'd like to know if I can setup a home network and turn one of my desktops as the server. Also, I'd like to run Windows Home Server but I really have limited knowledge about setting up a network. Any help would be appreciated.
Windows Home Server would probably be overkill for a simple home network. Your router will handle everything from DHCP, DNS, IP's etc. for the network. You can easily put a new HDD in one of the computers and then set share the HDD over the network and then you would have a NAS(Network Attached Storage). Give the computer that will have the shared HDD a static IP, and then go to another computer, type backslash backslash and then the IP of the shared HDD computer(\\192.168.1.xxx), the shared folders on the computer will show up, and If you share the entire HDD it will show up, then you have an HDD that everyone can access, just like a simplified home server
What do you want your "server" to do? If you just want a central place to store your files, follow Schm1tty's advice, but with a little tweak.
Rather than having to remember your computer IP addresses (and figure out how to assign a static one which carries other difficulties) I would setup a windows Workgroup. By default, Windows machines are on a workgroup (network), usually named something like "MS_HOME" or "WORKGROUP".