upgrading imac to yosemite

I have an iMac I got in 2006 and seems to work ok still. Currently running 10.6.8. Lately newer version of Firefox crashes a lot and sites like GMail and YouTube are not happy with the version of Safari on this.

I'm thinking it's time to upgrade and wondering if I can upgrade it to OS X Yosemite with no problems. Would love to get a new iMac but can't do so for another while. :/

The specs for Yosemite say iMac 2007 or later. I'm not sure of its model year on mine, but it shows iMac5,1 as model identifier. It has Intel Core 2 Duo processor 2.16 GHz and I'd upgraded its RAM to 3GB and HD to 1TB a little while back.

What do you think - possible & safe?