I’ve invested in a black MacBook with 2GB of RAM (purchased separately of course, as Apple charge far too much for RAM upgrades). It’s an exceptional machine; the specification is great for the price, it’s aesthetically pleasing, and the ability to run Windows (preferably using Parallels Desktop rather than Apple’s Bootcamp) makes for a perfect development environment. My only concern is the occasional, quiet mooing I hear in the background
If your designing and/or developing for both Mac and PC (and if you’re not, you really should be), the Apple’s Intel-based Macs are far and away the best solution.
