The tradeoff, of course, is that the Mac natively runs OS X, while the PC is Windows-based.
How much does doing this all yourself save? Well, if you use the Loop chassis, the Core i5-2400S, 4 GB of DDR3-1333, Intel’s DH61AG motherboard, a low-profile cooler, an 8x DVD writer, the WiFi Link 1000 card, a 500 GB Western Digital Scorpio Black hard drive, and Logitech’s MK250 wireless keyboard and mouse kit, then you’re spending around $780. The cheapest iMac costs $1200, or $420 more.
Use some of that savings to grab a small mSATA-based SSD, an operating system, a slim Blu-ray drive, or just pocket the difference.
Intel tells us the Thin Mini-ITX form factor will continue evolving. Particularly in the face of Windows 8, touch-based screens, WiDi, 7-series chipsets, and more comprehensive support for the Ivy Bridge architecture (and its improved graphics engine) should augment the integration of all-in-ones even more.