the knock off version of the wireless adapter works with win7 64-bit. i have that OS on the htpc and i've tried that adapter on it and it works fine.
the knock off version does not work on any apple device. i think i heard someone was rigging up some control software but no updates lately.
the plug-in xbox controller works on both pc's and xbox's (duh!)
the original ms wireless pc adapter is not made anymore, so the knock off version is the main way to go. unless you buy it used. (im not selling mine!