Dual Booting Windows and Linux sounds complicated, but really is not hard at all. As a precaution, back up all important data from your computer. Burn important files on CD/DVDs or look into a product similar to Norton Ghost. Make sure you have your Linux cd/cds on hand. Also make sure you have a partition resizing program on hand. This guide will be based on the program Partition Magic.

1) Close all running Programs

2) Defragment your hard drive by going to Start->Programs->Accessories->System Tools->Disk Defragmenter

This moves all stored data on the hard drive to the front of the drive

3) After defragmenting, immediately restart your computer and boot into safe mode. If you don't know how to boot into safe mode, see my tutorial here. Don't run any applications, just immediately restart and boot into safe mode.

4)After booting into safe mode, run a disk error check on your hard drive. To do this, go to my computer and right click on your C drive. Select properties. You should be greeted with a windows similar to the one below:

 

4) Now, click on the Tools tab and select the Check Now button. When error checking is complete restart your computer.

5)Start the Partition Magic program.

6) On the left hand side of the program window, you should see a menu looking similar to the one below.

 

5)Click on the "Resize a Partition" icon.

6) Go through the wizard to resize your partition. I recommend give Linux at least 6 gigs of your hard drive.

7) When finished, click Apply in the lower left hand corner of the partition magic window. Partition Magic will restart your computer and make your specified changes to the hard drive.

8)When Partition Magic finishes, it will bring you into Windows. Insert your Linux disk into your CD drive and restart your computer.

9)Your Linux Distro should start its installation process.