The sony rootkit is installed and only installed if you play one of the music cd's that incorporates the copy protection.
As it installs the player it puts the rootkit on.
The first removal patch that sony issued actually caused more problems than it cured. It will kill windows.
This page has a bunch of links to good information on this windows killer.
http://tinyurl.com/bgejl
For the most amazing breakdown of this rootkit check out this blog.
http://tinyurl.com/auyjl
More reading on the subject. Including a list of cds that will infect you.
http://tinyurl.com/cdwze
Is there a saving grace? Yes!
Believe it or not Microsoft to the rescue?
http://tinyurl.com/bmw8g
All of this is just another reason to control the content that is put into a companies computers.
Good Luck
Lee