I've been going through the same strokes recently and have been thinking about updating my primary laptop (a Lenovo T60 from 2006, one of the first dual core computers) to something more modern. I checked out the MBP and the MBA, but there is just something that concerns me about support. I know Apple's initial support is pretty good, but I am more concerned with things like battery and fan replacement a few years down the road. I've purchased two new batteries for my T60 in the five years I've had it, and had to replace the CPU fan once. With Apple's new designs doing either of these things would involve getting Apple involved, the latter probably requiring a logic board replacement. With my T60, I was able to open up the entire laptop very easily, and get four year old parts from Lenovo directly without any hassle.
The majority of consumer-oriented Windows laptops out there suck, but once you step up to "business class" machines, everything really improves. Right now I am eying another Thinkpad (will be my 6th), specifically the X220 with the i7 dual core, IPS display, and SSD for ~$1500.
