Worth to upgrade?

a dual to a quad is always a good upgrade

http://www.anandtech.com/bench/Product/144?vs=288

It will only make a difference in Skyrim, basically. The Ti shouldn't max your CPU in other games.

Why not invest in a good HSF and push your Clarkdale up over 4ghz. These chips easily break 4.5+ and could take much more overclocking than the coveted Lynnfields. There are plenty of Clarkdales out there running at 5ghz on air. Don't forget you also have HT, so while you might be limited to 2 physical cores you're not going to see much degradation running games that utilize 3 cores.

If my thoughts weren't obvious, I'll be clear. Save your money for upgrades elsewhere.