When your computer is working smooth..
a) Startup Disk
Everyone of us has experienced the frustration if the computer won't start. This problem is more difficult to handle than software related problems. The easiest way to make sure your computer 'starts' every morning is to create a bootable install disk.
Go to Start | Settings | Control Panel | Add or Remove Programs and choose the Startup Disk tab (should be the last tab). Just insert a blank floppy in the floppy drive and click 'Create disk'. Once you have created your boot disk, just put it in your computer if it starts acting up.

b) Backup Registry
It's a good practice to backup your registry setting if in case...
Start - Run - regedit
From Registry Menu choose Export Registry File...
Save the file somewhere on the hard drive. Next time if you think there is some problem with the regisry, double click on this file.
Remember - A Stitch in Time Saves Nine.