If you're deciding between a 13-inch MacBook Pro and a 2.26GHz Core 2 Duo ( Macworld rated 4 out of 5 mice ), you'll find a 5 percent performance benefit with the 2.4GHz MacBook Pro. The difference in Speedmark scores between the two systems was largely based on the Call of Duty results, which favored the new GeForce 320M graphics.

Even with the new graphics, the relatively small increase in processor speed was not enough to boost the new low-end 13-inch MacBook Pro's performance above the last generation's high end, a 2.53GHz model, which received a Speedmark 6 score of 123, a score that falls between the scores of the two new models.

The new high-end 13-inch MacBook Pro with a 2.66GHz Core 2 Duo processor received a Speedmark 6 score of 126, a little less than 7 percent faster than the low-end model, besting that system in each individual test. The new 2.66GHz system was 2.4 percent faster than the last high-end 13-inch 2.5GHz model, again with graphics results making up most of that difference in Speedmark scores.

In most tests, the new 2.66GHz 13-inch model was a few seconds faster, though in a few tests, like the ones using iTunes and Aperture, the older model was a little faster. For some reason, Compressor was much faster (9 percent) on the 2.53GHz mid-2009 model than on the new 2.66GHz system. We'll do some more digging on that head-scratcher soon.

Comparing the new 13-inch MacBook Pros to their 15-inch siblings, you can really see the performance difference that the Core i5 and i7 processors and the discrete graphics can make. The 15-inch 2.4GHz Core i5 model was 16 percent faster overall than the 13-inch 2.66GHz Core 2 Duo MacBook Pro. The Call of Duty test showed the GeForce GT 330M graphics in the 15-inch model could display 75 percent more frames per second than the fastest 13-inch model. Cinebench was 24 percent faster, Aperture was 32 percent faster, and Photoshop was 10 percent faster in our tests. I'm sure there are a lot of people wishing that Apple had a Core i5 upgrade available for the 13-inch MacBook Pro.