There's less yak shaving on a mac vs. linux/windows. If linux had minimal yak shaving and a really good quicksilver replacement, (and a bit more elegance to their program suites) I'd go there in a heartbeat. But there is always tons and tons of yak shaving and i've found laptop hardware support to be painful.

You can get a refurb macbook pro with comparable specs to a dell laptop for the same price right now. And the macbook pro has a better build quality. Worse comes to worse, you can install windows xp on it and get a better machine out of it. Macbooks also keep their resell value a lot better than the typical laptop too, so you can sell them used for alot higher vs. an equally specced dell.