windows os updates and restricted users

You need to set it to auto download and install the updates automatically w/o user intervention.

Yes, Microsoft: how *do* small network admins easily keep their boxes patched automatically without blowing big hole in security or setting up sus server? inquiring minds want to know!
think we have catch-22 here. ahem. the 'design' fosters users to comprimise security to get secure....imho. ahem. sorry.
as far as i can tell, you don't get the automatic update prompts unless you are logged in with an account that belongs to administrators group.
btw you have all latest sp's and critical updates applied, yes?
as you know just because user doesn't get prompts doesn't mean box can't get updated automatically. so are you saying box is not staying updated? that when you login as ordinary usr and go to windows updates and scan for critical updates you get error or it shows you some updates that should have automatically installed are available and/or some waiting to install? if so search support.microsoft.com mskb for your exact symptoms/error messages.
you can use group policy in AD or you can 'force' the updates on the box however via hacking the registry. (don't thank me thank microsoft) here is a link to good article:
http://support.microsoft.com/kb/328010/EN-US/
or search support.microsoft.com mdkb for 'automatic windows updates'
because we actually need lots more detail about your setup. how many users. how many computers? what version xp?

1) Login w/ Admin. privileges.
2) Access System Properties by either:
a) Right-click on "My Computer" icon on Desktop & select "Properties"; or,
b) Select "Start"/"Settings"/"Control Panel" & from there select "System."
3) From within "System Properties" select the "Automatic Updates" tab.
4) Check the box labeled "Keep my computer up to date."
5) Select the Setting "Automatically download the updates, and install them on the schedule that I specify."
6) Select "Every day" or a specific day of the week, as desired.
7) Select the time of day desired.
8) Click on "Apply."
9) Click on "OK."