I never was in the position of having to save all my files.
Actually, you were. You should always back up any files that are important to you. There are only two kinds of hard drives: those that have failed and those that will.
That said, here is how I back up my own files:
First of all, you need media to back them up. Most computers these days have a CD burner. This is probably the cheapest way to back up data, since CD's are around thirty cents and will save about 750 MB of files. Since I don't know how many files you have, or how much space they require, I don't know how hard this will be for you.
You cannot backup programs or your operating system. These need to be reinstalled from their original media. Program installation files which are downloaded from the internet can be saved. Sometimes, with such things as antivirus programs, it is better to get the latest version of the program anyway.
You need to backup your favorites unless you are one of those people who don't often use them.
You can back up your email accounts, if desired, but some people don't care.
You should have any passwords you use saved somewhere, so that you can get back into sites that require a password, such as this site or ebay or other forums. You need to know your username and password for your ISP.
Many people keep most of their files in the My Documents folder. (I don't - I keep them all over the place.)
You need some kind of program to use to burn the CD's. I don't use backup programs because I hear too many horror stories about how the restore didn't work. You can use a program like Sonic or Nero to back up files, and if you don't have anything like that but you're using XP, you can download CDburnerXP
Depending on which program you're using, you would backup your files by simply adding them to a data disk. If you have lots of music files or lots of pictures, you can back up as many as possible on a single CD. Backing up your Favorites/Bookmarks can be done from within whichever browser you're using - in Firefox, it's "Manage Bookmarks" and then File -> Export and then choose a folder to put them in, such as My Documents. You can then restore them by going to the same place and importing your bookmarks backup.
To install your operating system, you'll need the operating system disk and the 25-number Windows key. If you don't have that, you can use a program like Magical Jellybean Keyfinder
to find out what it is and write it down. The number is usually on the holographic sticker on the side of the computer. Note: if you have the operating system on a partition on the hard drive itself and no actual install disks, you may have a problem.
Using the instructions for whichever program you're using, back up your files to the CD by adding them to the list that you want to back up. When you have them burned to the disk, put the disk back in the drive and make sure you can open the files - no sense having a backup that doesn't work.
If you have any programs such as Quicken or Microsoft Money that have data, you should follow those programs' instructions to back them up. You can back them up to the hard drive, then when you're burning the backup files to disk, you can include those files in the backup.
Take your time. Be thorough.
If you have any games that you're part way through, chances are you can back them up, too, and save the backup to CD's.
If you have a fast internet connection, you can back up stuff online. There are many places that will let you do this, such as this one. Just do a google search for "backup online." Then, when you get Windows and your other programs re-installed, your backups will be secure and ready to download back to your computer.
You do not have to backup all the contents of your hard drive - just the files such as pictures and music and anything else that you want to keep. If you want to back up things like your email account, let us know what you're using for email, and we can help you back that up.
If you have an address book on your computer, back that up, too.
Another option is to get a new hard drive, install Windows on it, put your old hard drive in as a slave drive and copy the files to it. But, for myself, I would never mess with anything if my data wasn't already backed up. I recommend getting in the habit of making regular backups.