My fan is making a skipping noise

Hey all. My fan has been very loud lately at its default setting (1000rpm). It sounds like it is skipping or hitting something inside. I took it to the apple store and they said something is causing it to over work and i should reformat the computer... which i know is incorrect. Does it sound like i need a new fan? I do a lot of photoshop work and my computer gets up to 190+ degrees often, so the fan gets a lot of work! thanks!

oh, i also notice when i speed it up to about 1400rmp, the skipping stops.

i have a macbook pro core duo, 17".

my thoughts exactly. which is why i didnt get it done. that seems to be the go-to thing when they dont want to do work, or they dont know exactly what's wrong. ill take it back out there i suppose. good ol apple care.