Ummm. From my brother's experience with his computer, the files are sometimes still recoverable, even though you put them in the recycle bin. This is because, I think, windows will not remove the information from your drive, rather it will just not recognize it, and will if needed overwrite it. If you want to really make them go away, try something like internet eraser. Of course with the technology the government has, they still might be able to figure out what you are so worried about, which if it is some of the sick stuff that shows up on some searches (i.e. kiddie porn), then you should be worried.