installing a new processor

i mac desk top 24 3.06 GHz processor

I have 2009 i mac desk top computer and i want to change the processor in it. What it has now installed in it is a 3.06GHz intel core 2 duo. I want to change it two a 3.06 GHz intel core i5 . Can i make this change on my computer and where would be the best place to buy this processor and is it hard to install it. and what brand do you think i should install in my computer.

Apple iMac "Core 2 Duo" 3.06 24-Inch (Early 2009) Specs

Identifiers: Early 2009 - MB420LL/A - iMac9,1 - A1225 - 2267