Intel Core 2 Duo and Yosemite

I have a iMac circa 2009/2010 running a 2.66GHz Intel Core 2 Duo, with 2GB RAM installed.

If I was to upgrade to Yosemite, even with an upgrade to 8GB RAM, would this be enough to run Yosemite well? (Well as in comfortably useable, not freezing and becoming sluggish each time you open a browser tab or app).

If not, what would the most recent version of OS X I could run and maintain a quick machine? Currently on 10.6.

Mostly general use, but occasional use a home office machine, running Adobe CS4 etc.