"OK Computer" is an awesome album to start with. I don't know how "In Rainbows" sounds, and can't give you a frame of reference. "The Bends" is good and pretty straightforward. "Kid A" and "Amnesiac" are on the experimental side and chancy if you are just getting in to them. "Hail to the Thief" is also very good, but maybe not as immediately catchy as the earlier stuff. It's one of those that grow on you.

"OK Computer" is widely considered a seminal album and is a safe starting point.

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"Nothin' up my sleeve. . ." --Bullwinkle J. Moose