I just discovered SpyBot's immunization feature. Should it be done before or after a scan and removal of spyware or doesn't it matter?

Also, what's the difference between the Immunize button in the left column and the +Immunize button on the top-center (the right hand panel)?

I don't think it really matters, but it is probably best to immunize each time you run SpyBot - that's what I do, run, remove, immunize (often times everything that should be blocked already is if you run SpyBot regularly). As for the Immunize Button in the left column, it just opens the Immunize Screen, the +Immunize actually activates the Immunization . . . hope this helps.

As Engadine says, it doesn't matter. 'Immunise' is kind of separate feature to the 'scan for spyware' one in Spybot. It uses the same database of spyware as the scanning operation does though.

The time to immunise is when you download any updates available. Then, when the Immunise Button is pressed, a message will come up to the effect that there are a number of (newer) items that can be additionally blocked. Choose to immunise against these.

Providing there were no updates downloaded, it won't be necessary to re-immunise when the spyware scan is run. All known bad products will already be blocked.

It's important to check for updates prior to scanning for spyware.