porcupine tree recommendations?

So far what I've heard of this band I wasn't very impressed with, a couple songs were kinda catchy such as "The Sound of Muzak" which I heard on this site.
What do you recommend? What album is most "proggy" and how is it more "proggy"?
Does PT have anything that I must listen to immediately before I buy anything else?
I'm open minded for the most part with prog, my collection is fairly balanced I just lack in the PT section immensely and I want to know if thats a problem or not.

If you want really proggy PT I'd recommend Up The Downstair and The Sky Moves Sideways, if you're interested in the band improvising Metanoia is worth a listen, Deadwing, In Absentia and Signify are good if you want to explore their heavier side.

^ I'd also recommend Lightbulb Sun - my "secret favorite". But it's out of print - it's better to wait until it is re-released.

My favourite is "Signify". Anyway i recommend you to start with "Coma Divine - Live In Rome".

To explore both sides to this band I suggest you try and get both

1995's "The Sky moves sideways" (the 2cd edition that is!), which sees the band exploring spacey ambiences with electronics and guitarsolos;

and

2005's "Deadwing" which is their latest album and is a superb mixture of their space rock past and their new metal grounds.

All of them?

Lightbulb Sun, Signify and Deadwing are my favorites though.