I just checked my noise floor running my Lenovo laptop with Win 7. I was just curious, but I must be one of the lucky ones. I removed my power supply and checked the noise floor. I found no difference whatsoever.
Maybe the Lenovo power supply that runs this laptop is a good one. I did check the noise floor in the AM BCB, where noise should be at a high point.
Just my 2 cents worth. For those that have a laptop, try pulling the power cord, and make the laptop run on battery power, then see if your noise floor drops.
Have a FDM-S2, with Wellbrook Loop, on a Lenovo E550