Sure you can chase after all of those Spy/Adware.
or you can use a scanner that will remove it for you (very much like a viruscanner).
I use AD-Aware from lavasoft - It's free and efficient.
get it on Major geeks:
<a href="http://www.majorgeek.com/index2.html" target="_blank">http://www.majorgeek.com/index2.html</a>

Cheers,
Gabriel