I got into them fairly late, because I wasnt a huge fan of the band that led to The Mars Volta (At The Drive-In).
I walked into a Hot Topic of all places and heard The Widow off of TMVs Frances The Mute cd and fell in love. That album is AMAZING, without a dubt one of my favorite albums ever. However, you have to be aware that this is not your normal listening experience. There are huge blocks of time on the cd that are just background noise...people talking, cars driving by, random noises. To me though, if youre in the right mindset, you fall into the world that cd creates.
You know how I know those guys are amazing? I dislike everything about their music...half the lyrics are in spanish, long solos that go nowhere, garage rock post punk noise, artsy prog noodling around...and I still absolutely love every minute of it!!!
Oh..and their bassist was in 80's metal band Racer X, so thats a bonus.