I had serious problems on my 2007 macbook pro when I upgraded from Mavericks to Yosemite, so I had to go back to Mavericks. The computer worked fine and, as I was considering purchasing another macbook, I decided to try to upgrade to El Capitan as a last attempt to keep this workhouse of a computer. To my surprise, I saw that the app store allowed me to download the upgrade and I figured I had nothing to lose. I thought everything was going to freeze up and not work, but everything worked perfectly. Please note, that I do not use any processor (graphics or otherwise) intensive programs and use this computer mostly for email, web browsing and excel work. Therefore, I would not do the upgrade if you intend on using any programs that work fine on the current OS you are running. That being said, the best thing about the upgrade is that it gave this old horse new life and allowed me to use imessage, as well as pick up phone calls from my iphone, on the laptop. I was surprised it work. Now, I'm wondering if I...