I only scanned through, so I may be wrong, but I believe I'm the only person so far to have listed these first two in my PC history 
BBC Micro (Model B I believe)
BBC Master (No idea which this was)
8086 Laptop
386 SX 33MHz (was an AMD chip)
All the below are self-built systems
Intel P133
AMD K6 233MHz
Intel P2 266MHz
AMD K6-2 500MHz
AMD Athlon 1333 MHz (Thunderbird)
AMD Athlon 1600+ (Mobile chip - laptop)(palomino core)
AMD Athlon XP 2000+ (palomino)
AMD Athlon XP 2800+ (Barton)
AMD Athlon 64 3700+ (San Diego)(Overclocked to 2.86GHz)
Intel Core2Duo E6600 (Overclocked to 2.93GHz in a Shuttle)
AMD Semperon 2800+ (Barton - Shuttle)
AMD Athlon X2 6000+ (current main rig)(won't overclock due to crappy mobo)
AMD Athlon XP 2700+ (Thoroughbred - Media PC)
Next upgrade ... Intel Core2Duo E7200 is looking interesting.

BBC Micro (Model B I believe)
BBC Master (No idea which this was)
8086 Laptop
386 SX 33MHz (was an AMD chip)
All the below are self-built systems
Intel P133
AMD K6 233MHz
Intel P2 266MHz
AMD K6-2 500MHz
AMD Athlon 1333 MHz (Thunderbird)
AMD Athlon 1600+ (Mobile chip - laptop)(palomino core)
AMD Athlon XP 2000+ (palomino)
AMD Athlon XP 2800+ (Barton)
AMD Athlon 64 3700+ (San Diego)(Overclocked to 2.86GHz)
Intel Core2Duo E6600 (Overclocked to 2.93GHz in a Shuttle)
AMD Semperon 2800+ (Barton - Shuttle)
AMD Athlon X2 6000+ (current main rig)(won't overclock due to crappy mobo)
AMD Athlon XP 2700+ (Thoroughbred - Media PC)
Next upgrade ... Intel Core2Duo E7200 is looking interesting.