(One thing this is not is , which does much the same thing but with Nvidia chips only. Remember, in this case you're switching in the background between Intel's integrated graphics and Nvidia's discrete chip.)

The 330M, according to Apple, is about twice as fast as the Nvidia GPU in the 13-in. model, and about 20% faster than the Nvidia 9600M GT used in the last MacBook Pro line. That's something gamers should notice, because it allows for more details in graphically intense games. I'm not a gamer, though. When it comes to graphics, I judge how well a laptop plays back high-definition digital video: Are the colors rich and saturated? Is there any image "smearing" or obvious pixilation?

On those counts, the MacBook Pro's sharp, LED-backlit screen looks great. In fact, I watched three back-to-back episodes of Mad Men at full-screen resolution with the brightness turned all the way up and they looked almost as good as they do on my hi-def TV at home. As for battery life, at first I didn't see a major improvement over previous MacBook Pros. Apple says to expect 4.5 hours of use when watching DVDs full-screen at full brightness; I had to plug in the MacBook Pro after 3.5 hours of use. So I created a new account and tried again. Voila! I managed just over five hours of movie watching on battery power. (I haven't yet figured out what may be running in the background in my account that cuts down on battery time.)

When it comes to more mundane tasks such as surfing the Web over Wi-Fi, editing Word documents, checking e-mail and sending out tweets, the battery life is also better than before. (As with DVD viewing, I saw the biggest improvement logged into the "clean" test account.)

First, I set up the 15-in. MacBook Pro as I would normally, with the screen at about 80% brightness. I also turned off some of Apple's aggressive energy-saving settings in the Energy Saver preference pane, because I like to keep the screen from dimming on me if I turn away for a minute or two. While doing a combination of word processing, surfing the Web over Wi-Fi and listening to music through iTunes, the battery needed a recharge after 4.5 hours.