nitehawke, I love you. that little light was driving me crazy.
It was slightly different for my Lenovo G550 with 7 pro 64bit and a Broadcom card, so I'll stick that here in case anyone finds it helpful:
The registry keys were here:
I changed LedBlinkFast from -1 to 0 and that stopped the blinking with activity. The other keys are:
----dunno what these do----
----also don't know----
I've attached a screenshot of the relevant registry keys.