Ken Hough's Website
Linux can be set up to run to run as part of a “dual booting” system allowing it to share a hard drive with an existing Microsoft Windows installation. This option is offered by most distros. Note that the Windows system must be set up BEFORE installing Linux. Microsoft Windows is not friendly towards other operating systems.
I have set up dual booting systems many times in the past and it can work well. However, there is a “gotcha” due to the fact that if (or when?) a re-installation of Windows becomes necessary, information in the master boot record of the hard drive will be overwritten by Windows and depending on the way in which Linux was set up, access to Linux might be lost. This situation can be avoided, but not without an appreciation of how hard drive partitioning, boot records, and boot flags work, and how to ensure that boot information is written into the boot record of a primary Linux partition rather than into the master boot record of the hard drive.
SETTING UP A DUAL BOOTING SYSTEM IS A SERIOUS OPERATION. If it goes wrong you might loose existing data, including other operating systems. If you do decide to do this, then DO first make a FULL system backup onto another hard drive.
I would be happy to explain this in detail to anyone who is interested in setting up a 'dual boot' system.