UPS probably not going to help. Have you checked to see if their are any bulging caps. I would test memory and hard drive with some kind of diagnostic too. Those types of things can cause intermittent issues.
For sure, I don't know how they make money of something like $200 dollars. They need to concentrate on making a tablet that rivals the Ipad. Netbooks are for people with small hands anyway.
Good wireless is normally pretty expensive. You're looking at $600-1000 for a 1 MP camera. You may want to try out a CCTV camera kit that comes with DVR, a few cameras and cabling, etc. You should be able to get decent enough facial to see the person. If the area is dark when you are checking...
Any Microsoft or Logitech webcam in that price range is pretty decent. Cheap for webcam is normally $10 and under. Even then you'll find some good ones. Syba and Sabrent normally make decent cheap ones in the $8-15 range.
If you want cheap webcam, refurbished Logitech ones as they are...
If you still hear the noise when the power supply is only plugged into the paper clip, yeah, it's most likely something wrong with it and time to replace. If that is not the case, I would check the board for blown caps.