Depends on the subject. It's always good to use updated material for REG because of all the deduction and phaseout changes. BEC you could get away with older material. Not sure about FAR or AUD since I haven't studied for them in a while.
Roger's site usually has a pdf you can print that has all the changes.

"Luck is what happens when preparation meets opportunity."
Roger & Ninja
FAR: 75
AUD: 73, 81
BEC: 71, 73, 82
REG: 68, 82