You can do a speed test at; Pick the location nearest you:
http://www.broadbandreports.com/stest?more=1
You could also scan your computer for adware and spyware using:
* Ad-aware -
http://www.lavasoftusa.com/support/download/
* Spybot S & D -
http://www.safer-networking.org/en/download/index.html
You can also use:
* HiJackThis -
http://www.spywareinfo.com/~merijn/downloads.html
The first link will show you what speeds you are getting (compare this to what you are supposed to be getting) and the other links will help you see if you have anything on your computer that you won't want to be there.