Eight months ago Intel’s first dual-core CPUs outpaced a similarly configured laptop running on a single-core processor by 30% when performing two tasks simultaneously.

Now the Core Duo's successor, Core 2 Duo, claims even better performance, plus 64-bit support. But should you be kicking yourself for jumping the gun and buying a Core Duo notebook earlier this year?

PC World tests indicate not. Whereas Core 2 Duo desktops racked up dramatically higher test scores than their Pentium D-based counterparts, notebooks got only a small performance boost from the mobile Core 2 Duo (formerly code-named Merom). Battery life for comparable products was similar.

We tested three Core 2 Duo-based notebooks: a US$1,906 (£1,292) Dell XPS M1210 equipped with a 2-GHz T7200 chip; a $2,164 (£1,467) Gateway M685-E desktop replacement with a 2.16-GHz T7400 chip, and an all-purpose $1,499 (£1,016) HP Pavilion dv6000t with a 1.83-GHz T5600 chip. The biggest performance increase over laptops with same-speed Core Duo CPUs was 7% - enough to shave a few seconds off day-to-day business operations, but nothing more.

In our tests, Core 2 Duo didn't affect battery life much. Core 2 Duo chips cost the same as Core Duos used to, so you can expect fire sales as Intel begins to discount the older Core Duo chips. In view of the modest performance gains, you should think long and hard before paying a premium for a Core 2 laptop.