This gives you a relative scale of performance.
http://www.tomshardware.com/charts/2009-desktop-cpu-charts-update-1/PCMark-Vantage,Marque_fbrandx14,1394.htmli7 > i5 (high-end) > core 2 quad extreme > i5 (low-end) > core 2 quad > i3 ([very] high-end) > core 2 duo > i3
Notice in the chart, the i3 is clocked at 2.93 GHz (high end) just to feature above some Core 2 Duos. The core i3s that you normally see are 2.1-2.5 GHz.