Dual core? Not enough information. Could be better, or could be worse than all the rest.
Core i3 is more recent CPU design than Core 2 Duo.
You'd need to compare model numbers to know which CPU would be more powerful though. Generally, at the same price point, the Core i3/i5/i7 will perform better than and C2D/C2Q.
Compare specific CPU models here: http://www.cpubenchmark.net/
Won't be long before the new Sandy Bridge Core i3/i5/i7 CPUs will be coming out that should lead the pack in performance.
My own desktop has an E6300 2.8GHz Dual-Core (as I said) which cost me $89AUD.
That means it would be less in USD, right? Any ix series processor costs more that $100.
My friend has a 2.4GHz quad that I have on very good authority was cheaper than equivalent i7 core processors. I have not checked his specifications further but through personal discoveries I will push my point forward.
Maybe this ONLY applies to my E6300 when compared to certain ix models but I speak only from personal experience and not from full research. You are probably more correct than I am and I apologise for any wrong information I display.