I just reinstalled Windows 7 in one of my older computers, and somehow the windows update tool got stuck in the Checking for updates process for hours. I rebooted the computer a couple of times hoping that would speed up the process but no, it seems like the tool picked up the process right from where it left it.
I used the original recovery manufacture DVD for the installation, and maybe something got corrupted along the way, because I had never seen Windows 7 taking that long to update.
It was time to hit Google for a solution.
after trying many recommendations I found on the Internet, what seems to have worked for me was installing this update. After 3 minutes of running that update, I got the notification in the system tray that there were a bazillion updates available.
I hope that save you some time!