Xbox wirless controller and Win7 problem.

I've bought one of those generic wireless receivers for Xbox 360
controllers.

A lot of rig-amore-ol getting a driver to install but eventually got
Win7 to use the Wireless Receiver option from MS's download Xbox Utils
software.

Controller not seen yet good batteries in it and green led is on on
reciver.

I plug in a charging cable on the controller and plug it into usb port
and presto controller seen and works properly.

Problem is it's not wireless connection. I also wonder just how it's
communicating with the pc, e.g. is it using wireless or the usb port?

If I disconnect either device (receiver or controller) contoller
disappears.

Anyone offer any clues what's going on? And how to get it to not need
charging cable would be nice also or not need receiver even nicer as it
would make controller usbale on multipule pcs I have without having to
install reciver.