hi....................>>>
such things i know about this is that windows 95,98,2000 they are all based on msdos if you remove this dos your window will not work while removing msdos in xp or vista nothing will happen to them as they are free from effect of dos(disk operating system)
Both Win 2000 and Win XP uses the same kernel architecture and first one is server OS & second one Client OS. As a client Win XP can make use of all new features provided by win2003 like new security settings, policy settings etc.
Win NT is old server OS and XP is client OS for new server versions like 2000 & 2003. Active Directory support is inbuilt with XP but NT does not support AD and Group Policy objects. NT uses NTFS 4 file system but XP NTFS 5.
There is basically not much difference between WIN2000 & WIN 2003. WIN2003 introduced new partitions in Active Directory like System, Config etc. and new security settings in GroupPolicy. At the trust level Forest trust is new in WIN2003 and Domain renaming is possible. IIS is not installed by default in WIN2003 & some other not commonly used services are set to Disabled by default..