Some clients not showing up in the WSUS console.

The clients were imaged but we use Sysprep to create the image. I know this because the ones that are showing up were imaged also the same way the ones that are not showing up. Its something I never thought of however.

Ok then, let's try something on one of the workstations that isn't reporting properly:

Copy this to a CMD file:

reg delete HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate /v AccountDomainSid /f
reg delete HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate /v PingID /f
reg delete HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate /v SusClientId /f
cls
@echo Triggering detection after resetting WSUS client identity
net stop wuauserv
net start wuauserv
wuauclt /resetauthorization /detectnow

Run it on from one of the misbehaving PCs.  Let ne know if it shows up.

Reference: http://www.wsuswiki.com/ClientFAQ

These commands did not work, but I just found out that the workstations I am having problems with were built with an image and sysprep was not run on them. Apparently there is some issue with sysprep and SP2 of XP that has something to do with profile moving or creation. Anyway, we are going to test this out by running a utility called
New SID on one of the problem workstations. If it shows up in WSUS after this, then we know for sure that is the issue.
I found out from my Help Desk that over 500 of these laptops were given out like this (no sysprep) so I have a lot of work to do.

Just for the record: you not only have a lot of work to do, you also have lost any chance of getting support from Microsoft for those machines, should you ever require it: "Microsoft does not provide support for computers that are set up by use of SID-duplicating tools other than the System Preparation tool. If an image was created without the use of sysprep, Microsoft does not support the running of Sysprep after the image is deployed as a way to bring the computer back into compliance."
The Microsoft Policy Concerning Disk Duplication of Windows XP Installations
http://support.microsoft.com/?kbid=314828

With more than 500 users, the Help Desk should know better ...

I'd say so.

All those machines not only don't report to WSUS, but also share the same SID in the domain...

You can run Sysprep on all of them now, it'll just go through the mini-setup wizard when you reboot.  You'll have to put the workstations into Workgroup first and delete the computer account then rejoin them.

Lots of work for sure.

Yes indeed. I may have over estimated a bit on the amount. I went back and asked again. Its not 500 but its a lot. Thanks for your help in this.

My solution - get the staff that made the mistake to fix it.  They won't learn anything unless they have to fix their own work.  Given the scope of this issue, they'll never again forget or ignore the correct procedure for imaging!

I know, I'm a bit of a PR#*@!  :o)

Running sysprep now won't help with the support, though; note the comment from above: " If an image was created without the use of sysprep, Microsoft does not support the running of Sysprep after the image is deployed as a way to bring the computer back into compliance."
The image that is deployed has to be prepared with Sysprep, so basically the helpdesk should re-rollout the machines with a properly created image ...