Following options come to mind:
1. Use as door stop,
2. Use as boot anchor,
3. Use as weight on fishing / crabbing line.
Seriously, just keep using XP. The system won't crash and burn. If you plan to access the internet, then I would recommend installing a good free AV and then updating the AV regularly.
That's if you are using MSE, since you will no longer be receiving MSE updates.