I have the same tuner, and I ran into the same problem. Just cancel the media center installation, it will never finish ( I waited 24 hours ... ).
There is a download on hauppage that will update the tuners. It is not very specific, but I imagine it actually updates something on the tuners. You run the program, and you need to leave the tuner in the usb. I would actually plug off as much from the usb hub as possible.
After the update, the tuners work perfectly.