Comment Keep XP (Score 1) 1
Does everyone really need XP updates. Just switch to a sane Browser. Stay away from MS Office. Uninstall JAVA. Uninstall Flash and use HTML5. Install a good Antivirus and proper Firewall. Use Foxit Reader rather than Adobe Reader. In short, just secure XP and it should be fine for another decade or so.
Do something *useful* with the money rather than paying for Windows upgrades over and over.
Finally, try out some Linux distros on a few machines. [ducks an avalanche of chairs from Ballmer]