koala

SpywareBlaster just edits the registry and system settings to try and prevent spyware and is an extra layer in your protection, whereas a realtime program is always running in the background, scanning files as they are created or accessed.

It's a good idea to have both, as they won't conflict with each other, and SpywareBlaster uses no system resources at all once it's been updated and closed. If you only want to install one of them though, go for the realtime MalwareBytes.