Thanks Evo. Switching off hibernation doesn't change things, and once I was satisfied with my system I used Disk Cleanup to remove all but the latest Restore Point to minimise the space used, so that should have minimal impact.
But I think I've found out what's happening.
MS KB article 328848 describes Dual Mode updates for XP. I think I ended up with that this time (I didn't have it on the last installation) because this time I stupidly did a did a few on-line updates before I remembered I hadn't yet installed SP1. The article explains what happens - basically the Autoupdate system has detected the order in which I've done things and thinks I might one day want to unstall SP1, so it stores a pre SP1 version of many applied updates, even those applied
after SP1 was installed. That gives one the option of uninstalling SP1 and if one does that the system will automatically install the pre SP1 version of any updates installed under SP1.
Devilishly clever, but I don't think I'll ever uninstall SP1, so I'd just like to switch all this off and get the disk space back.
The article just describes the process, not how to switch it off.
Maybe I have to wait for SP2, but I was going to let the rest of the world test and de-bug it first. In the meantime I want my disk space back
Not another re-install, PLEASE
AA