I've seen the occasional episode of Power Rangers, but that was quite a while ago. On satur/sunday morning the tv channel always aired some episodes, and sometimes my sis and I watched it. I've seen two episodes of Ultraman, but that by accident. I didn't even known "8" (channel name) aired it. Gotta say it was quite amusing (and I wasn't the only one in the house to think so... and I'm the only one who watches Japanese things).
I knew about Super Sentai, yes. Even before the Dutch magazine Aniway wrote an article about the genre, but that did give me more information about it none the less. Before it was more a term I'd heard somewhere.