No Service Packs in WSUS updates

I have recently set up a test environment for for WSUS which all seemed to go without any problems.

There is one PC that requires a Service Pack update (From XP SP1 to SP2) and I have just noticed that there are no service packs in the list of updates on the WSUS server. I synchronised the WSUS server again just to be sure and still no SP’s listed.

Any thoughts on this?

Cheers.