Spyware is named because it is software that does something to jeopardize your privacy, such as recording the Web sites you're visiting so that companies can pitch products based on your surfing habits. Aside from the privacy and security issues (which are major), spyware also slows down your computer because the software is always running in the background, using processing power and, in some cases, sending extraneous data over your Internet link. It can greatly diminish the speed of your Internet connection.
The best program to get rid of it can be found THIS PAGE. It's a free download and gets rid of alot of it.
The leading spyware company is called "ZANGO" and thier spyware can be found on many computer systems. To remove it specifically you can download thier free tool in zip format HERE or you can go to thier HOME PAGE and do it there. Good Luck!