I don't buy computers any more, just buy parts and let my son put the parts together to make a computer. I got a kick-ass computer for gaming a few months ago that way so that I can play Diablo 3. And I probably saved about 25% or more over the cost of a ready-made computer of comperable power at Best Buy.
Exactly a year ago, I bought an Acer laptop with an i7 processor, 8Gb ram, and 1Tb HDD. It was a bargain at the time, and it works great, just a little less powerful than my desktop computer at home (from 2.5 years ago). It's slick, has a full full-size keyboard, decent size screen, yet light-weight and portable. Although it mostly sits in my office, it's nice that laptops today can be good enough as primary work-computers because you don't have to suffer of reduced means when travelling or moving around (from office to labs).
If you include non-PC computers, then my latest acquisition (last summer) was a new micro-controller board (Quanser HiQ) for my lab's satellite-emulating unmanned aerial vehicle. It runs a hard-real-time micro-Linux kernel and allows us to control the UAV via wifi (which is not without its challenges in a hard-real-time system). Pretty good overall, although I had to squeeze every clock-cycle out of the code to get it to run the control systems and filters smoothly.