[onetwo_threefour]

^ That was me... maybe, I know I've mentioned it on this board.

In general affect is a verb, but there is a specific, medical/psychological use as a noun where 'affect' = expressive demeanour. "Joe has a flat affect, meaning his body language and facial expressions show no emotion."

Similarly, effect is generally a noun, but it can be used as a a verb occasionally. One may 'effect' a change to a situation by doing something to it. "Studying for the exam allowed him to effect an improvement in his result."

However, in normal usage, affect is always a verb, and effect is almost always a noun and you'll rarely screw up follwing that guideline.