Found this on the Spyware Blaster forum, Graham, hope it helps:
"SpywareBlaster is certainly most useful when used with Internet Explorer v6, however it does have some value when the primary browser is something other than IE6.
The SpywareBlaster cookie protections only work for IE6. As for the primary protection, that being the "killing" of known spyware related ActiveX controls, this is not actually done within IE but is made through global settings stored in the Windows registry.
ActiveX controls can be run by means other than calls from IE, though IE is clearly the most ActiveX integrated application. If you have any of the SB protected ActiveX controls on your system, or if these get called (to be either downloaded or executed) through any other means than IE, they will still be killed by the protections from SpywareBlaster.
Using SpywareBlaster has almost no downside. It doesn't take system resources because it doesn't run in the background. It doesn't seem to conflict with any Windows applications. It takes very little disk space and updating it is at most a two-minute job, once every week or two. Yes, it is best with IE6, but it is still of some value with any other browser running on your system."So, what it seems to be saying is that Opera is not directly supported, but having SB certainly won't do any harm, and could help with ActiveX controls. That is a fairly old post though, and SB has since been updated. It definitely now supports Mozilla, but not Opera as far as I am aware.
http://www.wilderssecurity.com/showthread.php?t=16799&highlight=Opera+browser