FAQ779-4784 may help.
windows XP running very slow
thread779-796508
How to remove a second installation of a Windows operating system from a partition
2 copies of windows XP installed on my system
thread779-846333
Slipstream Service Packs
thread779-900263
How to Set up and Use Automated System Recovery in Windows XP
Every Service Pack is cumulative, meaning that it contains all earlier updates. So if SP2 is not embedded into your XP CD (as in all recent versions of XP) you will need a copy of the SP2 CD. It is freely available from Computer Stores or your friends might have a copy.
This will still leave you some 50 or so updates to be re-installed. Not much you can do about them but download them again.
For future reference you can manually download updates from the Windows Update site and save them to disk. Maybe you know of such a person who has and would then let you copy them?
The trick with the above procedure is to let Windows manually scan your computer and tell you what updates are required. With a list of the updates in your hand, you then use the Administrators option link on the Windows Update site to access the Windows Catalog of updates, where you can then save them to disk. When you know what updates you require, go here and look for the link called "Find updates for Microsoft Windows operating systems". This will be available after a Brief Update of the Windows Update engine.
Find updates for Microsoft Windows operating systems.
How to download Windows updates and drivers from the Windows Update Catalog
Have you any friends on Cable or Satellite that could help you out and save the updates you require to CD for you? Maybe you could take your computer to a repairer and have them download everything you need, assuming they have a fast connection. Or just go to bed one night and leave the updates to trickle down at the rate of about 8 - 10 MB's per hour
As for Anti virus software, some save the updated definitions in folders and you may be able to find and save your older updates and pick up what you miss through the normal update process.