Get a hold of Nick Mason's book 'Inside Out', gives a good fairly balanced view of the band's history.
Original band were Syd Barratt, Roger Waters, Rick Wright and Nick Mason. Barratt had major problems with drugs/fame and burnt out early (Wish You Were Here is a tribute) and was replaced in the band by Gilmour.
Towards the end of the record making history relations between Waters and Gilmour wrecked the band and Gilmour only reluctantly agreed to play the reunion.
Recommended listening (mine); Pulse Live double album with a bit from all eras, Wish You Were Here, DSOTM, Atom Heart Mother, Piper At The Gates Of Dawn. Apart from Comfortably Numb, The Wall is pretty rubbish, typical overblown 70's concept album.
If you can also find the DVDs for Pulse and Live At Pompeii.
I saw them live a couple of times including during the final Earls Court concerts but the best was Dortmund in 1977 when then did WYWH and Animals, flying pig included.
FWIW, Mason owns one of the most amazing collections of sports racing cars and is a nice guy.
Stick in on your iPod, fire up a joint, close your eyes and away you go.
Careful with that axe Eugene! 8)