Win XP is a client OS from Microsoft(MS), which is used by most of the users in the domain or a network. This is comparitively cheap as compared to server OS from MS. There are 3 version of MS that a user can use. WinXP Home edition, WinXP Pro(that can be connected in a domain) and WinXP Media Center(developed for entertainment purposes)(u cannot join it to a domain).

Then there are win 20002003 server OS. Which are respncible for managing a domain or a workgroup. They require H/W configuration higher than client OS's. There are various version of win2000

Win2000 Pro(that acts as a client OS and can be joined to a domain or workgroup)

Win2000 Server(which is mostly used to ACT as a server)

Win2000 Datacenter(used to store large amount of data, can act as a Fiel server or a SQL data server)

Win2003 has no client version, it is only avaliable as a server OS in the markert.

Already any one has explained about Win-XP & Windows server 2000. I will
explain you about Windows Server 2003.

1. In Windows Server 2003 there are three versions

i) Enterprise Edition :- It's the still largest server in all three server. It can support 32bit as well as 64 bit edition. A lot of
explanation is there but...
ii) Standard Edition :- It can support only 32 bit
iii) Web Edition :- It is used as web server.