I Really want to keep copies of the updates installation files
I would be interested to know why .....
If it is to help in a future clean install download SP3
, which contains all the updates since SP1
and slipstream it into your XP CD (retail)
Otherwise do as I suggested ....
If you want to keep copies of the updates installation files they can be downloaded from Windows Update using Administrative options to your hard drive.
It is likely that not all are there as some may not be intended to be installed at a later date.
Windows/Microsoft Update > Use Administrative Options > click the Windows Update Catalogue link > type in Windows XP into the Search box. The results exceed 1000 updates, not all of which you will require - so good luck