At the very least an annual repartition, reformat, and reinstall keeps your system healthy and happy.
Personally I wouldn't own a computer that I don't have every driver disk for, OS, etc.
Passwords should be backed up, open firefox, get into your passwords and print the page of passwords for the sites you visit. (Keep it secure of course)
Computers are kind of like pickup trucks. Lots of stuff gets loaded, unloaded, all of it leaves a certain amount of debris, dirt, and grunge in the corners. Every so often you just need to get out the power washer and clean it out down to the corners. If you don't it will rust out and fall apart on you.
If you can't handle a repartition, reformat, and reinstall of OS, pay someone to do it for you.