Track pokerinfo off play on pokersites

[Buffel]

I play alot on the internet mainly at Paradise almost from the start of that site.
I heard that it is possible to track some info about the play of others and off your own play, I heard some things about pokertracker.
Can someone give me some info about those programs and where to get them, the costs, and if they work well and are interesting and easy to work with.
Sorry for the bad english I am from Belgium.
Thanks in advance.

[Deicer.]

www.pokertracker.com
Excellent program !