Well I went out to the web and found which update you needed to prepare your machine for Win 8 and installed that, and just a bit ago ran Win update and updated everything and still nothing.
Typically our main IT group handles all PC updates for the company but we're basically testing Win 8 so I'm just working through issues like this myself, not sure if their software has blocked some of the needed updates though (although it worked fine on my work Surface Pro). Anywhere online I can get the updates needed?
You are probably on a volume license of windows 8. You can not do a store update for 8.1, sorry. It sucks