Processor Intel Core i3 (540) Intel Core 2 Duo (8400) Cores 2 2 Max RAM support 16GB (1066/1333 Mhz) 16GB (800/1066 Mhz) 3 Ghz/6MB Cache/1333Mhz Clockings 3 Ghz/4mb Cache/ FSB N.A FSB clock Operating System Support 64bit Support 32bit/64bit The greater cache size for the core 2 will allow for faster speeds and better video editing and stuff. You will also have a better time overclocking the core 2 processor better than the Core i3. Core 2 Duo Support both standard and higher RAM. You need 64bit Operating system in Core i3/i5/i7 Processors with more than 4GB RAM. The Core i5 will certainly be better off than all the rest. The i5 has the same architecture as the i7, just on a smaller socket. If you use your computer for basic tasks such as word processing, email, surfing the web, etc., a Core i3 processor is more than enough to handle all of that with ease. Core 2 Duo offer enough performance to do stuff like video editing and gaming, and more than enough performance to do basic stuff like word processing, internet surfing, and email. -for better understanding of your processors, now its your turn to decide.