Hello dear Mac users, I now recommend those of you who have at least an Intel i5 processor, and 4GB of RAM or more to upgrade to El Capitan. Although the Intel Core 2 duo processors are compatible, unless you have more than 4 GB of RAM, I would I would say proceed cautiously. If you are buzzing along fine with Yosemite, OS X 10.10.5, then there's no real hurry to upgrade. But I've received many calls from people who need a newer operating system to be able to use some applications. And unfortunately, unless you have a bootable installation disk, you have to upgrade to the latest operating system through the app store. If you cannot upgrade because your system is too old, it's time to think about getting a new computer.
As with Yosemite, if you have an earlier copy of Microsoft office 2011, you can expect some problems and instability. I think it's a good idea to upgrade to Office 2016, either in individual perpetual license form (sold as a download), or the subscription to Office 365.