I have no idea either.
One thing you should keep in mind is that you are comparing your old Turion X2 to the brand new Core2Duo series which will be leaps and bounds better. Would it be worth it? Maybe, but it depends on how much your current system is struggling with the programs you are running.
1. "old Turion X2"? I just bought this laptop last November.
2. What is the speed difference between the Turion 64 X2 2.0GHz chip vs. Core2Duo 2Ghz chip? Can you point me in a direction to see a comparison chart to reference?
3. Also, my computer really isn't "struggling", but POWER, man! lol (I use it for web development & graphic design)