Not a very precise answer, but then that wasn't a very precise question.
Core 2 Duo is a whole family of processors, whereas i3 330m is a single, very specific processor.
i3/i5 is the newer generation, and is generally better, but for battery life, the CULV Core 2 Duo (su4100, su7300) still can't be beat.
Graphics wise, the i3 330m has the new Intel GMA HD IGP which is somewhat superior to the 4500MHD that usually comes with the CULV Core 2 Duo: it can handle HD, but forget about any serious gaming.
Essentially, it depends *what* you want to do with it...