First PC 'we' (family) had was a 386, 25mhz Beast, Probably 4mb ram etc.
After that, and when I first got into overclocking was a P75. I worked out that you could run it at 90mhz. Without a heatsink, and you can burn your finger when you touch it!!
Moving on then to a 400mhz AMD K6-2, which was the last box parents bought at my request, and the first PC I built myself. Oh, and it had a 33.6k modem for the internet too. A cheap (about £30 then) one, took me around 3 months to get the damn thing working, but afaik it still works in emergencies now, in another box ofc.
That machine had several ram upgrades, a new chip eventually etc, but somewhere along the way I acquired a P3 450, and a Couple of 200-300mhz Cellies as my own, after that I was away.
Athlon 1000 was the first rig purpose built for overclocking; sat her quite nicely around 1400 I think, for £50 less than my m8 paid for his 1400 stock. This was the point where I first dabbled with water too.
Then moved onto... wait first rig?

Meh its nice reminising, ignore me if you like
Anyways, Dual P3 1ghz Setup on an ECS mobo. Never ever got that to work without hanging for a second or two in every 20. Couldn't work it out.
Then after some time messing about and scrabbling rigs out of not much I bought a shuttle & a 2200XP. Was shortly followed by a full size mobo, 2500XP-M, and a Thermalright SL-97 I think it was, Huge copper beasty. Had some fun with that. Then when Finances permitted, moved to Dual core with my X2-3800.
The rest is in my sig.