i3 is Intel's latest version of dual core desktop processors. They employ 32 nm size, an integrated graphics core, & hyper threading. Includes i3 530 & i3-540.
The Core 2 Duo was Intel's older twin core processors, usually with 65 nm size, no on-chip graphics or HT.
i want to know what is the fast processor
Both are fast; the i3s more so than the C2Ds