I was obsessed with that band for a few years from when I was 16.
I have all their studio records and live albums, dvd's etc. Just collected everything. Seen them live a couple of times.
Their 90's albums are very much band-driven instrumentals with a lot of electronics and flutes, but their last few albums the 'real' drums are more and more disappearing, making them sound more like an Ed Wynne solo effort.
Get any of their albums, just preferably NOT one of their latest three (Spirals in Hyperspace - The Floor's Too Far Away - The Yum Yum Tree). Those three records can be seen as Ed Wynne solo records, as they're not collaborating as a true band nowadays. As a result, much of the stuff on these records are synthy and programmed. I definately prefer their more organic, jammy sound.
Be sure to check out 'Live @ The Pongmaster's Ball DVD', 'Spice Doubt: Streaming in the Ether', and 'Erpland' for their jam/folk/ethnic sound. Then get 'Waterfall Cities' and 'The Hidden Step' for a perfect blend of band-driven and electronic stuff.
Trivia:
* Frontman and guitarist Ed Wynne is referred to by Jordan Rudess on the Metropolis 2000 Commentary track. During the instrumental section of 'Beyond This Life', Petrucci kicks in with a guitar solo and the psychedelic effects are layered on him.
* Their song 'Sploosh!' was used in a BMW commercial (that's pretty weird for such an unknown band).
* Porcupine Tree once opened up for Ozric Tentacles.