What is your goal - what do you need to have happen?
Each VM you create will have an IP address. You should be able to communicate between the machines as if they were standard machines on a network.
Okay im studyin MCSE,so i just need a server VM and 2 xp VMs to carry out practice exercises/labs,nothing fancy , they just need to communicate with each other as though it were in a real networking enviroment so just need to know if there are any configurations required for Virtual Pc in order for my request to work
Windows 2003 is listed as "unsupported" under Virtual PC. http://en.wikipedia.org/wiki/Windows_Virtual_PC#Support... - it may work, but it may not. You could look at some of the vmware products - vmware player now supports creating VMs and supports a whole range of guest OSs. I've used it myself, I like the interface/controls better anyways.
Just google "windows server 2003 setup" and you'll find a ton of guides.
Virtual PC can support Microsoft Server OS's. I used it for a school project to run Server 2003 with SharePoint and it worked out fine for me. Just make sure you are using the latest version of Virtual PC.
Anyway, to run your virtual pc's within their own network, you just have to make sure that the VM network settings are set to "Local Only". You also have to make sure the IP's are all on the same network and subnet.