Well with noise created from hum, ground loop, etc., there's no "silver bullet". My older Acer laptop had a 3 prong plug for the power supply and using a ground lift plug eliminated my noise (maybe that's where my loop was broken?). A ground lift plug can be bought for 1-3 dollars at a hardware store (Lowes, Fred Meyer, etc.) What they look like is on one side you can plug in the "3-prong" plug and on the side that goes into the wall there is only 2 prongs... the 2 blades.
With my new laptop PC I have no noise issue. :D
The only trouble I have is if I stand with my guitar pickups right in front of my monitors. :(
Don't do that and I'm golden.