Turning off Suspend

Looking at a strategy for deploying Windows XP Service Pack two on several
of our customer sites. Most have some users at the end of a limited
bandwidth connection. My current plan is as follows:

1. Set updates to be applied at 3:00 AM, with automatic reboot.
2. Approve SP2 at end of Business on a Friday.
3. Instruct users beforehand to leave their PCs turned on over the weekend.
4. Be onsite Monday morning to address any issues.

Big fly in the ointment here is that most of machines on most sites are
configured to go into suspend after 20 Mins of inactivity. (IBMs ship this
way). In most cases users do not have admin rights on the local machines, &
so cannot change this either. It does not seem possible to configure this
with a GPO, & manipulating the registry seems a little less than straight
foreward. Can anyone suggest a utility, or som method where I can turn off
suspend on the workstations in the domain so that SUS can do what it needs
to over the weekend?

Thanks
Mal Osborne
MCSE MVP Mensa