(2-part post):
I'm very confused!!!
The '2002' suffix is only used to refer to the Microsoft Office suite (and to its individual components, such as Word, Excel and Access). It's got nothing to do with your operating system (Windows XP). That will have been installed onto your computer together with the latest 'service pack' which was available at the time. So you've got the original XP operating system
or XP (Service Pack 1)
or XP (Service Pack 2)
or XP (Service Pack 3).
(There are actually 'Home' and 'Pro' versions of XP as well, but that's not relevant here).
The Service Packs are FREE downloads, so there's no reason that you should need to pay anything to update your operating system. (And I can't think of any reason why you would need to upgrade Microsoft Office components to get security software to run. You don't even need Microsoft Office on your computer at all!).