I had trouble getting the platform update to "pick up" also. But the advice given below is correct - if you're patient. I had just ran update, just installed Vista SP2, all that. System said I had no more updates needed AT ALL. But when I followed the instructions about go to Windows update, and tell it to "search for updates" sure enough, after a LONG time (5 minutes?) it came back with a list of 12+ "Important" updates! One was the Platform upgrade, and another was the "Supplement to Platform Upgrade" - so now they are installing and all seems to be going well.