I thought I would post a poll out of curiosity. My oldest PC that I currently have is a no-name OEM that's now 7 years old or so. It started acting like it was about to kick the bucket last year but it has magically come back to life since then. The specs:
P4 Northwood
@2.6 Ghz
1.75 GB of RAM (originally had 256 MB)
NVIDIA Geforce fx 5200