While there are similarities between "Taurus" and "Stairway to Heaven", I wouldn't call it a direct copy. Spirit was one of those bands from the 60s that were always on the cusp of recognition but never quite made it big. I think the lawsuit was indeed frivolous.
I am reminded of the riff from "Iron Man" that has been used in so many songs (including a country song). Sometimes a progression of notes just exists on its own and you happen to get lucky when a song you performed that contains that progression blows up. Fun fact: while most people recognize the "Iron Man" riff, it existed for at least thirty years prior to Tony Iommi recording it in 1970.
"No matter where you go, there you are." Buckaroo Banzai
There are two types of computer users: Masochists and Linux users.
If you would like help or further details on a technical discussion we're having, email me at bnhelp (at sign) keepusiel.net .