Ok, more research... With more thought given, I've come to the conclusion that I'd really like the possibility to run Mac OS X on whatever machine I put together. Thankfully there are some good resources for this, including forums where people are trying/recommending various product configurations: http://tonymacx86.com

Here's what I'm thinking about right now. And this is subject to change depending on when I pull the trigger.

CPU: Intel i7-3770K 3.5GHz (which I'd like to overclock to 4.2GHz)
MB: Gigabyte GA-Z77-DS3H
RAM: 16GB (2x8GB)

A complete system can be had for $754 on Amazon right now. Excluding keyboard/mouse/display, which I have plenty of, but also excluding a replacement CPU fan which will probably be a good idea for overclocking. I can probably drop $90 off the price by not buying an additional drive as I can probably find one or two around here as well.