Dual-Booting

Dual-booting means installing two operating systems on your computer and, at start-up, choosing which one to launch. Each OS runs independently of the other, with its own settings and its own installed programs. You can install two or more instances of Microsoft Windows XP or of Vista, or any combination of Win XP, Vista, Linux, and older Windows versions.

Partitioning

Before starting, you need either a separate partition on your hard drive or a separate drive; if you install Vista on the partition where Windows XP is already installed, Win XP will no longer run. Open My Computer, and make sure it shows multiple hard drive icons (one for each partition). Now check whether the second partition has enough space for Vista (at least 20GB to 30GB if you plan to install major programs). If not, or if you don't have a second partition, start with step 1 to create one.

Partitioning programs such as Norton Partition Magic make partition creation and management reasonably easy. Use the Resize command to shrink your existing partition and then the Create option to make a new one. After a reboot (which can take some time) your new partition will be in place.

At this point, you install Vista, either from within Win XP by inserting the Vista disc and letting Autorun do its thing, or by inserting the disc and rebooting the system (as long as your PC is configured to read the optical drive before the hard drive).

You have two main tasks during the installation. First, on the "Which type of installation do you want?" screen, choose Custom; selecting Upgrade changes your Win XP installation into Vista, which of course won't result in a dual-boot environment.

Then, on the subsequent screen, you have to tell Vista where you want it installed; this is where you choose the new partition.

After that, just wait for the installation to finish. Your PC will reboot itself more than once, and with each reboot you'll see your new Boot menu, with earlier version of Windows at the top and Microsoft Windows Vista next.

Use the arrow keys to select the OS you want to load, and press Enter.