I upgraded my 2007 macbook pro to 10.9.2. Noticed it was running hotter than normal.
Thought it might have been power related..time for a new battery.
Then, thought maybe the hard drive was working too hard...so I put in a new SSD Drive... Used the iFixit guide to replacing the disk drive. THEN, I got down to business.
Using the iFixit guide to replacing the fans, I pulled each of them, blew them out with dust-off, and using deionized water and cue-tips, I swabbed out the heat sinks and air channels, and blew each of them out with dust-off. Finally, I used a soft wipe and HP cleaning fluid (DI water) to gently wipe down the exposed side of the logic board. It had a fine blanket of dust that had to cut down on heat transfer.
Used my trusty 00 Philips and T6 Torx and spudgers throughout, of course. The iFixit guides were a great help
When fixing thermal problems, it's best to start with the thermal control systems. DUH. Didn't need the new battery or the solid state drive, but it DOES run faster and last longer on battery.
If you have a 6-7 year old laptop, I guarantee you that there's significant dust in there, and a thorough cleaning will keep it cool, and lasting much longer.