Wording might be a little off, but:
Device Manager > Unknown Device > R-Click > Update Driver Software > Browse my computer for driver software > Let me pick from a list of devices installed on my computer > Microsoft Common Controller Class (if Win7)/XBox Peripherals (if Win8) > Wireless Receiver
Also, if Win8, run the device driver installer in compatibility mode for Win7 and as admin.
Edit: HDE?
Edit2: Be sure to download the http://www.microsoft.com/hardware/en-us/d/xbox-360-wireless-controller-for-windows from MS rather than using the driver on the included disc, x64 I'd imagine. Once its ring shows you as player 1, it should then work for all *applicable games.
*PC Oblivion doesn't support the controller as Skyrim/Fallouts do, that is you'll need XPadder or something like it (no rumble)