(Preface: you need a “live cd” too boot into an environment from which you may delete or rename the “pending.xml” file, to do this, I used the free and open source Ubuntu Linux distribution.)

Step-by-step:

1) find a friend with a working computer, CD-Burner and blank CDROM. Visit the Ubuntu download site: http://www.ubuntu.com/getubuntu/download

2) download the desktop edition ISO
3) burn the ISO to disk (if you don’t know how to do this do a bit of googling - it’s beyond the scope of this fix)
4) once burnt, boot your broken Windows Vista computer, but use the appropriate key combination to change the boot settings to tell it to boot from the CDROM

5) the Ubuntu CD should offer you a language selector and then the option “Try Ubuntu without modifying your computer”

6) Ince Ubuntu has booted, go to the “Places” menu in the top menu bar.

7) Within the places menu, you’ll see some “disk drives” listed, you should be able to guess which one might be the one that is your Windows Vista C Drive by it’s size or name, e.g. “75.4GB disk” or “Presario” or “System” etc… it depends upon your computer.

Once you’ve figured out which one it is then click it (don’t be scared to try each entry in turn)

9) a disk icon should then appear on the Ubuntu desktop that you can then double click and explore.

10) Confirm that it’s the correct disk partition by looing for familiar folder names such as “Users”, “Windows” etc.. (if not try one of the others as described in step 7)

11) navigate to the following folder: windows/winsxs

12) locate the file “pending.xml” and rename it by pressing F2 on your keyboard and editing the file name to something like “pending.xml.broken” perhaps.

13) restart the computer via the ubuntu System -> Quit… Restart options

14) remove the live cd when prompted.

15) let the machine boot up back into Windows Vista, it may go back to the “configuring updates” screen again - but don’t panic - be patient. It should switch after a while to say “Welcome” and eventually take you to your normal Windows Vista desktop.

This worked for me, I hope it works for you too.
Good luck.