I recently restored my old PC from 2006-ish to 2013.
And yes, I know it's dirty. I'm too lazy to clean it.
HP Pavilion a1250n
CPU: AMD Athlon 64 X2 3800+
RAM: 4x512MB DDR-266
GPU: ATi Radeon X1950 Pro 256MB (had others before that I don't remember)
OS: Windows 7 Pro (originally ran XP, then Vista, then 7 Starter, and finally 7 Pro).
I've had other PCs before this one, but this one is the oldest one I have detailed memories of.
I originally had some 80GB drive in it (probably a Maxtor). In 2011 or 2012, I switched to a fresh install on a 40GB Maxtor Fireball 3. Because I like sentimental things, I couldn't bring myself to erase that drive and do a fresh install, so I grabbed a blank 100GB Maxtor that I have and did a fresh install on it.
It originally had a 350W Enermax PSU, but the cable spaghetti got annoying, so I switched it out for one of my 350W InWin PSUs a few days ago. I also swapped the CPU fan because the bearings on the original were long gone.
I think my very first PC was the infamous Patriot Computing Hot Wheels PC. I still have the CD book from it (with the original discs it came with).