Upgrading computer

My task for the weekend is to back-up the data on my computer and upgrade it. I don't think the upgrading will be so bad, but I have accumulated so much "stuff" - my computer is loaded. It will take me many hours to back-up all the programs and information I need to keep. I'm afraid my tendency to be a "pack-rat" has spilled over to the handling of my computer, also. Wish me luck!