Heavy laptops: there’s no excuse
The way I see it, there’s no compelling reason to buy a heavy laptop. Light laptops are great because they’re portable. Their processors might be a little slower, but local processing power rarely limits what you can do with a computer these days. And unless you get a really tiny laptop they’re hardly slower. If you do get a tiny one then you’re trading reduced HCI-bandwidth for increased access to that bandwidth, which is often worthwhile. Today I’d probably argue that iPhone or iPod Touch is a pareto-optimal choice (sweet-spot) in this trade-off, beating out things like OQO and FlipStart.
But think about the longevity of these devices. Computers always slow down. In a few years, any laptop is going to feel really slow, no matter how fast it feels today. But if it’s a light, small laptop, then you’ll have something which is slow, but at least nice and portable. Some of my friends’ house has this ancient Pentium II Viao laptop kicking around the living room — it barely runs a browser. But it’s so small and portable that it’s still a reasonable computing device today. If your laptop is heavy to start with, then in a few years when it slows down you’re stuck with a heavy, slow laptop, which nobody nobody wants.