Low bandwidth - how to prevent automatic downloads

I'm trying to update my Dad's XP Home SP2 machine. He lives in the
middle of nowhere and only gets 28.8kbps connectivity. Automatic
updates is enabled and set to download automatically, but it's been so
long since he last logged on that there seems to be a huge backlog of
updates stacked up. The downloading updates indicator in system tray is
crawling along - 2% complete after more than an hour... I want to
install the most critical updates now from WindowsUpdate.com, and leave
the rest for later. However I can't seem to stop the automatic
download, which is hogging the bandwidth. I've temporarily switched
Auto Updates to "notify only", but the system tray icon still pops up
and starts downloading as soon as I connect online, even after having
restarted the PC. Stopping the Automatic Updates Service seemed to kill
it, but as soon as I restart it (needed to use WindowsUpdate), it
starts downloading again.

The critical updates I need to download are about 10MB - should be an
hour or so...

Many thanks for any help...

Cheers,
Andrew