Warthur
The first era of Porcupine Tree - in which the entity evolved from a one-man project to a fully-fledged band, and set forth a new and compelling vision of psychedelic space rock - is rounded off marvellously by this excellent live set (the 2CD version of which is the recommended one) which showcases a perfectly chosen selection of songs from the first four Porcupine Tree albums.
The band here perform the songs in substantially more loud and musically aggressive versions than the placid ones that appear on the original albums - the sound being somewhere between of early Pink Floyd as captured on the live disc of Ummagumma and the more intense jams the mid-1970s King Crimson occasionally got into - so even if you already own the originals, it's worth picking this one up for these very different interpretations of the songs in question. I wouldn't call this an absolute all-time classic, but it's certainly a very good example of the best sort of live album - one which both captures the feel of a live gig and at the same time presents the music in question in a new light.