Brendan,
just to let you know that your advice has all worked perfectly. I am now back to 51% free HDD, from just 11% at one time.

The update files were moved to the external HDD with no adverse effect to the computer.

I then had a look at the other 1.5gb file, Logmon.log. This, after googling to find out what it did, is to do with the wireless printer unit. So I then moved this file to the external HDD (15mins), and still all worked OK, as the wireless printer unit made another logmon.log file.

So now all the update and logmon files have been deleted.

I now have another problem that you may be able to sort out.

I installed a version of CD Creator, that I later found was unstable on XP and also unsupported by the company that took over LaCie. The program would not work, and even though I have uninstalled the complete program, I now get a warning box when I boot up.

The warning is "Devices or applications disabled. "CD Recording Software" will cause Windows to become unstable. Windows has prevented these drivers from loading. Click here for more details."

All the click here for more details does is go online and show that it could be one of three programs - two of which have never given any problems. So it must be the driver of CD Creator. How do I rectify this problem and prevent the window every time I boot up?

Sorry to be a pain, but I'm hoping you can come up with some remedy.