Too many PCs really,
Desktops:
Compaq P4 2.4ghz XP used to connect my film scanner via SCSI (It wouldn't fit into my Mac Mini), it also uses a program called Easy Thumbnails which i've yet to see a program that produces clear thumbs as good as this for for Mac.
HP Vectra P4 1.7 XP - used as a store for some PC images (Ghost server) - not worth selling to be honest.
2x HP P4 2.8ht XP - One was my main PC, the other was a Webserver (ran 2003 server for a while). The Mac Mini replaced both
Laptops:
HP Omnibook 6100 XP - I should bin this really
Toshiba (thing from work) Ubuntu - It is a work XP laptop, but I stuck Ubuntu on it just to see what it's like - Seems o.k. The idea is this is a guest computer, if people want to surf they can use this.
Macs: Mac Mini and Macbook