Hi Brian
Your IT Manager may have installed a legitimate copy of Windows XP on your computer. Legitimate in the sense that the company he works for may have bought a license to install it on a number of PCs throughout the company. Whether he has exceeded the terms of the license is another matter. It is a question of whether Microsoft sees your copy as genuine or not.
Do you actually have any problems running anything - apart from Windows update?
Have you setup Windows Update to automatically download updates? If so it should download certain files at various times, it is a matter of dependency. Sometimes you may get an update that contains 35 files in one go and at other times it will download just one. It has to download them in chronological order as each download is dependent on the previous download. This process could take a few days epecially if you installed an old copy of Windows XP.
The main file you have to watch out for is the Windows Genuine Advantage tool (WGA).
That is the file that will test to see if you have a genuine copy of Windows on your PC. You may want to read up about this WGA as certain groups are concerned about it and I believe there are ways of circumventing it. Microsoft bowed to international pressure and released details of an uninstall tool at:
http://support.microsoft.com/kb/921914while reserving the right to place WGA on your computer when delivering future automatic updates.
downside