Where to start

PC 1: Old Dell GX150 Pentium III 1GHz, integrated gfx, sound, 512MB SDRAM, 160GB IDE - now a testbed, OS is whatever I happen to be experimenting with, it's original function was replaced by PC 2.
PC 2: VIA EPIA
SP8000EG, VIA 800MHz CPU, integrated everything, XP Pro SP3, 1GB DDR, 120GB Samsung HDD, LiteOn Slimline all in a SNT AR600 case - sub 30W PC always on and downloading.
PC 3: Acer Travelmate 2201LCi laptop, now with Pentium 4 2.4GHz, 764MB DDR, 80GB HDD, Radeon 9000 IGP, XP Home SP2 - odd job and world travelling laptop.
PC 4: Athlon 1600+ on a AsRock K7S41GX, integrated video/audio, 512MB DDR, 80GB HDD, XP Pro SP2 - wife's PC - touching of the PC is strictly forbidden while there's nothing wrong with it

PC 5: AMD 5000+ X2, Gigabyte MA78G-DS3H, 4GB DDR2, ~2.2TB of HDD, nVidia 7600GT, XP Pro SP3 - general work/play horse, currently waiting for Radeon 4850 and AMD 95W Phenom 9750 to drop in price.
And hiding in the closet is my Amiga 3000 with CyberStorm PPC180, 132MB RAM, 2.8GB HDD, A2065, Picasso IV with all addons, AmigaOS 3.9.