AMD has lower Mhz processors, but the "pipeline", or how many steps the processor takes to perform an operation, is shorter than Pentiums. So while Pentiums can perform more steps since it has more Mhz, it isn't as efficient as AMD's. That's why AMD started naming their processors like 2500XP, even though it's clocked at ~1.8 Ghz; because it was meant to compete with Pentium 2.5 Ghz, performance-wise.
What will you be using your laptop for? Pentiums still hold the crown for media (audio or video) encoding, so if you'll be compressing a lot of video or audio, you'll save time with a Pentium. But for everything else, including gaming, AMD is equal or better than Intel. And when you take price into the equation, AMD's are MUCH MUCH less expensive than Intel's, for equal performance.
"Centrino" computers mean that there's a mobile pentium inside, along with an intel-brand wireless card. That's it. Laptop processors almost always slow themselves down when running on battery power, so a 1.7 Ghz laptop will actually be closer to 1.0 Ghz when it's not plugged in.
I recommend you save some money and get a Athlon-XP laptop, unless you're going to be doing some serious media-encoding. (in which case you'd be much better off with a desktop).
