Well, this isn't much of a comparison. The i3 is both a newer architecture and clocked faster. It also supports the current LGA1155 instead of being on a socket that is no longer used. So the i3 hands down.
Only reason to get an E7500 is if you already have the motherboard for it and you are doing a processor upgrade.
The move from the Intel® Core™ 2 Duo to the 1st generation Intel Core processors yeilded around a 15% -20% preformance increase at the same speed. The move from the 1st generation Intel Core processors to the 2nd generation yeilded an additional 10% to 15% improvement. In the end you are looking at around a 30% or more preformance improvement at the same speed from from the Intel Core 2 Duo to the Intel Core processor.