What is the difference between x86_64 and i386?

x86_64 is for 64 bit processors. i386 is for 32 bit processors.

All Core 2 Duos are capable of running 64 bit operating systems and 32 bit operating systems.

You want x86_64 as it will run better and allow you to have more RAM in the future, although if you are worried about compatibility, you could use i386. Personally I haven't had any problems with x86_64 on Linux.

x86_64 refers to 64-bit processors. i386 refers to 32-bit processors.

If you really do have an Intel Core 2 Duo, then it is a 64-bit processor. Some of the Intel Core processors were 32-bit. You can download either or - it depends if you want to run the 64-bit version. It gives you advantages of being able to use more memory (> 4GB per process, > 4GB in total without leveraging PAE) and in some instances will operate more quickly (and others more slowly).