The left fan in my Macbook Pro (it was a mid 2009) was getting really noisy, and it was driving me nuts.
Repair went smoothly, it was very simple and my computer is more silent than ever!
Just make sure you have a torx 6 screwdriver. You can get a set at Home Depot that includes the 6 with a bunch of other sizes for about $5. Very useful and you need it to take the fan out.