I'm doing a fresh format/reinstall of an Asus EEE (not mine) from its recovery partition.

This will restore its Windows XP (don't know exactly which SP).

What is the quickest / most effective way to get and apply all the updates?

I could set Windows Update to automatically install the updates, but this will still require some user interaction and will require (if I remember correctly) several reboots. I would like instead the process to be unattended.