Critics Curse Comet Cursors
That article will give you the basic gist of it. More information on how to prevent comet cursors from installing itself, or to disable unwanted features if you would like to keep them, can be found here: http://accs-net.com/smallfish/comet.htm
I hope this helps! Personally I don't care all that much about internet tracking, because I can understand why companies would be interested in seeing what pages I go to. But I don't like programs like that slowing down my computer - it works slow enough as it is. So I try to avoid things like comet cursors, gator, offer companion, web accelorators (which from what I've heard are more trouble than they're worth) mp3dancer, stuff like that.
"We know that, being a living part of the Mother Earth, we cannot harm any part of her without hurting ourselves." ~Lame Deer
"Forget not that the earth delights to feel your bare feet, and the winds long to play with your hair." ~Kahil Gibran