Exactly the same setup here, and same result. I'm hoping it fixes the fault described in these threads:I just checked Software Update about two minutes ago, and no updates were available. I am using a white MacBook from mid-2009, which was the last revision with the old MacBook form factor. I clean installed Snow Leopard when it came out, and I've always done Combo Updates.
That's what it says in System Update; it still does not say what changes were made in standard update (10.6.0>10.6.1>10.6.2>10.6.3) that wasn't done in the combo update (10.6.0>10.6.3).http://support.apple.com/kb/HT4014
Under the Additional Information section, bottom of page is your answer:
The Mac OS X v10.6.3 combo update also includes improvements provided in the Mac OS X v10.6.1 Update and Mac OS X v10.6.2 Update.
In order to receive all the improvements listed above, some systems require the Mac OS X v10.6.3 Supplemental Update, which is available via Software Update.
Tip: If you don't see the Mac OS X v10.6.3 Supplemental Update in Software Update, you don't need to install it.
Note: The Supplemental Update is for any system that was updated from Mac OS X v10.6 using the Mac OS X Update Combined v10.6.3, build 10D573. It is not needed on systems that were updated from Mac OS X v10.6.1 or 10.6.2, and it is not needed on systems that were updated from Mac OS X v10.6 using the Mac OS X Update Combined v10.6.3, v1.1.
Hope that helps....