Spybot Immunization

[stevenamills]

Towards the end of a tough cleanup, I frequently run Spybot Search and Destroy.

1. Add the HOSTS entries
2. Check BHO's
3. Immunize

It occurred to me that I really didn't understand immunization, which, I think, is a totally passive process. Some Googling really didn't help much.

Do any of you gurus and poobahs understand what is happening and is it a worthwhile exercise?

Thanks!