In and by itself, a rootkit isn't inherently dangerous. It's what malware and worm code writers can do with a rootkit that gives them a bad name. Knowing how to detect and eradicate malicious rootkits isn't easy and while some security experts recommend conducting system purges, others claim that new tools can help enterprises avoid cumbersome solutions. The good news is that now there are more and more tools and products hitting the market that aim to keep up with the increasingly sophisticated nature and attack strategies of emerging rootkits.

For more on fighting bad rootkits:
-check out this NetworkWorld article [1]