Im deciding weather to get a 27 inch iMac with the intel i5 2.66 GHz processor, or with the intel core 2 duo with 3.06 GHz, Which processor is faster?

The I5 is a considerably better performing processor as you can see in this chart: http://www.tomshardware.com/charts/2009-desktop-cpu-charts-update-1/Performance-Index,Marque_fbrandx14,1407.html

You can choose several different areas to consider but I normally look purely at performance. This provides a good level of measure of the overall capability and you can look at the placement of the charted processors. You can even compare to AMD if you like.

Personally I can't recommend the purchase of an iMac but if you are set on one of them the I5 is clearly the only choice to make. The reason is both newer technologies and that the I5 is a 4 core processor.

Good luck on your decision!

The i5 is faster, and it is much newer than a core 2 duo processor.

However, I pray you do not get Mac because they are expensive, incompatible with 99% of Windows programs, and did I mention expensive?

the i5.