Critical Preventive Maintenance.
Always be prepared with Startup Disks and a Full System Backup. The backup should be fairly recent. A properly planned Disaster Recovery Plan always requires incremental and/or full backups. The importance of this is easily demonstrated by Windows 98. Microsoft no longer supports it. Think how hard it would be to reinstall Windows from scratch, go find all the driver files, and then try to get all the critical updates. Good Luck! And that’s exactly what it is going to take, if you don’t have a complete back up.
Now look at the plentitude of XP critical software and driver updates. Service Pack 2 makes it much easier, but, again. How much time would it take to rebuild your XP computer? Would you know where to get the latest software updates, drivers, and patches for your computer, and all of your non-Microsoft apps?
(You might make an estimate in days.)