As you download a program and install it many times I have people that just click through everything.  They end up with extra programs and more toolbars.  As you install the free programs make certain that you read and look for boxes with checkmarks that have you agreeing to install toolbars or change browsers or change search engines.

As an example of clicking without reading and getting extra toolbars look at the graphic and note how much space is left to view things on the browser.