Simply configure Automatic Updates so that you need to approve the install.
That way, you can choose a convenient time to do so to avoid conflicts if
rebooting is required.

How to configure and use Automatic Updates in Windows XP:
http://support.microsoft.com/?kbid=306525
--
~Robear Dyer (PA Bear)
MS MVP-Windows (IE/OE, Shell/User, Security), AH-VSOP


Troy wrote:
> Hi all,
> Is there any way to stop Windows Update from automatically rebooting my
> computer after an update?
>
> My PC does alot of data processing / code comiling, etc. overnight and the
> problem with this is it doesn't seem to care that I have programs running
> and I've lost hours of work with this well-thought-through "feature".
>
> If Microsoft really thinks it's that important to reboot, the least it
> could do is query running programs to see it they can close safely.
>
> I've turned off automatic updates for now and am hoping someone has a fix
> for this.
>
> Cheers
>
> Troy