For that small a network, a server OS is probably overkill. Not to mention assuming you meant Craigslist, 99% of that software is likely going to be counterfeit. Legitimate retailers will all sell the software for about the same price, because that's what Microsoft mandates.
And also, if you have to ask a question like this, something like Windows Server is probably out of your depth. Even if it would be useful, which it probably wouldn't with only 5 systems. If you ever got closer to 10 and beyond, then we can talk about potential benefits of a server OS.
I hope you and your reader can help me with a net working question.
I have never written before. But need help, Iam useing xp and lantastic to network 5 computer together has been work very well
for year's a friend said I sould be use a dedicated server and software like, windows server ? windows server2000or,03,05?
should I change. would it help?
I look on Graigslist I see alot server software for sale very cheap
with Key new in pack.