PChucks Network: Don't Upgrade To Solve Active Problems

You see these questions in the forums occasionally:

I have a problem with my computers - I can't access each computer from the other. Since one computer was running Windows 98, I upgraded it to Windows XP. Now I still can't access both computers from each other. And the old computer runs really slowly. What do I do now?
I was having file sharing problems, on my Windows XP SP1 computer. Somebody suggested that I upgrade to Service Pack 2.

The advice, given frequently, starts with:

Did you back up your previous installation? If so, roll back there. First, fix the problems. Then plan the upgrade properly.

Before upgrading a computer to Windows XP, read Windows XP Professional Resource Kit.
Before updating a computer running XP, to SP2, read Get Your PC Ready for Windows XP SP2.

Prepare for your upgrade properly. Have a recovery process in mind, should the upgrade not go successfully. This means that you need to solve your current problems before you upgrade. Don't risk a triple whammy.

Downtime caused by the upgrade.
Downtime caused by recovering to the old operating system.
Downtime caused by having to fix the original problems with the older operating system.

Fix issue #3 first. Then upgrade.