windows 2003 5/10 clients quesiton

hi, im looking at windows server 2003 purchasing page. i like to know what are the differences between the full version (5 clients) and the full version (10 client)

25 computers (xp family/pro) connects to one server (2003 standard) does that mean only 5 or 10 client-machines in our company will be likely to connect to the server?

if not what does it mean with 5 clients and 10 clients? wish to hear your descriptions, thanks!

http://www.microsoft.com/products/info/product.aspx?view=22&pcid=4271ea85-f9e5-4986-80ec-5f53ade3740d&type=ovr