In reply to GridNorth:
Agreed, watch them in order. In fact read the books (in order of course) then watch them in order. I have read and watched these many many times, absolute masterpieces. Possibly some of my favorite ever vieweing of all time, ever. I first rented them and was blown away by how faithfully the atmosphere of the books and the cold war are recreated. I own the Doovdé box set now, an xmas gift. Treasured possesions.
The recent TTSS film with Gary Oldman was good to, but Obiwan Kenobi still makes the best George Smiley, by a country mile.
Enjoy!