Software Updates don't install till WUA is updated....

Hi,

I'm new to this so please bear with my lack of knowledge in asking the "correct question". I've been asked to take over this env. and am learning the tricks of the trade one by one...

Current setup:
Microsoft(R) Windows(R) Server 2003, Enterprise Edition SP2
WSUS 3.1.6001.65 - Configured to Sync from an upstream server of the same version.
SCCM 2007. V-4.00.6487.2000

We are distributing updates using SCCM.

We have clients (2003 and 2008, EE, R2, etc.) that have WUA versions 7.1.6001.65, 7.2.6001.788, 7.3.7600.163, 7.4.7600.226, 7.5.7601.175 and 7.6.7600.256.

Over the past few weeks, I've noticed a lot of clients do not install updates till the WUA is updated to 7.6.7600.256. The WUA updates have to be done to manually when I check for updates on the website. This is adding a lot of additional man hours to this process for 100s of servers..

I'm a bit lost as to why the WUA agents are not updated via SCCM/WSUS? Do I need to upgrade WSUS to SP2? 

Please advise on what would be the best way to bring all on the same page.

Thanks!