Originally posted by: Aluvus
The T2xxx series are not Core 2 Duos, they are Core Duos. They are based on the (slightly) older Yonah core, while the T7xxx series are all Merom. They lack the enhancements of the Core 2 series (macro-ops fusion and other fun tricks), but perform similarly to the T5xxx series (which are Core 2 Duos with 2 MB of L2 cache).
More on Core 2 processor naming.