I work in the Internet business and often hear people tell me that they have this great Internet speed and then complain how their computer seems to go slow on the Internet. While it can be viruses and spy ware, often it is you not getting the speed you were promised or pay for from your Cable, DSL or Wireless provider. Test it from time to time and call your provider if you are not getting what you were promised. Better yet, if they can not fix it, ask to have your price lowered to the speed you are actually getting and do not get charged for a speed you are not getting.
Just a way to save yourself some money. My friend had 5 Meg DSL from his local phone company and every time I tested it he actually had about a Meg and a half. He called in to get it fixed and they sent a repair man out and he admitted to the friend that he could not make it more. So the phone company stopped charging him for 5M and lowered his bill by $20 per month. Another friend on Cable quickly learned what a shared network does to your promised speed and made the cable company fix his to stop the massive fluctuation. Look out for your own money and do not be overcharged!!!!