My desktop unit is a self made unit, and is due for an upgrade.
Right now I have a dual pentium 3 with 1G RAM and a SCSI RAID harddrive config.
Memory and SCSI RAID are more important for overall performance than clock speed...but thats off topic here..
I have a friend who has been making his own desktops for ten years. Basically they cost about a third of what a similarly powered "store bought" costs and he enjoys it. He isn't an "over clocker" is anything like that, he just enjoys making them. And, he's gotten to the point where he can put one together in a couple of hours.
Like you said, off topic -- but it does show that computers are now commodities.