I5 vs Duo



I'm considering two builds that are totally equal in all areas, except the processor. Both have 4GB ram and the same low-end laptop GPUs.

One of the laptops has a Intel Core 2 Duo 2.4Ghz, while the other one has a Intel Core i5 2.26-2.53 GHz, depending on whether its the 430M or the 540M. I get that i5 2.53GHz is probably better than the 2.4 Duo, but what is the difference between the duo 2.4GHz and i5 2.26GHz?

I use both programs that would benefit from the i5, and programs that probably do not need all the features included with the i5

I think that programs such as Fruity Loops Studio 9 (a music program) would benefit from some of the features, and a variety of games that might not benefit from the i5. What's the best buy, the i5 or the duo?
The biggest difference the I5 has is its on a totally different architecture it is faster clock for clock then the core 2 also all the I5 mobiles are Hyper Threaded so its a dual core but has 4 threads so it looks like a quad to the OS. Get the I5.