this should be your album buying process:
1) Kid A (masterpiece beyond all expectations and Motion Picture Soundtrack is such an amazing way to end the unforgettable experience)
2) Amnesiac (just as great as Kid A, but a little different. I sometimes catch myself listening to this one more than other album, even Ok Computer which is my all time favorite. when i know i don't have much time, i'll usually quickly put on the last two songs, both of which i consider to be masterpieces)
3) Hail to the Theif (2 + 2 = 5, Sail to the Moon, I Will, Scatterbrain, A Wolf at the Door... those are by far some of my favorite recent songs, but the album as a whole is very addicting)
4) I Might Be Wrong (GREAT live CD. has one of my all time favorite songs: the live, piano version of Like Spinning Plates)
5) Pablo Honey (this can wait, but still has some great songs. many may disagree to make it your last purchase, but i feel it's not as vital to your health as the others)
if you're getting into Radiohead and love Ok Computer, i also highly recommend you check out their Airbag EP. they have some of my favorites like Pearly, Polyethylene, A Reminder, and Melatonin. The only problem with this EP is that it's very hard to find and can be pricey.
on another note, when you're done purchasing the rest of the albums, check out these great ones from other bands:
6) Interpol - Put On Your Bright Lights
7) The Arcade Fire - Funeral
8) Interpol - Antics
9) Sigur Ros - Ágætis Byrjun
10) Sigur Ros - ( )
...only then can you say you've lived a great life.