How to dual boot your Vista PC with Windows XP

Another big question from readers as a follow-up to last week's XP end-of-life post: How do I set up my Vista PC for dual booting with Windows XP?

For starters, it's true that some new computers will not be able to run Windows XP. The issue is one of drivers and mainly affects laptops: Some vendors have jumped so wholly to Vista that they're no longer making XP hardware drivers for their equipment. There's no real way around this, so check to make sure you can get all the drivers you need for your computer before you embark on the road to try setting up two operating systems on your machine. (You'll need them anyway.)

Also, be aware that configuring your machine to run Vista and XP side by side isn't the easiest thing in the world. It is certainly not overwhelmingly difficult, but if you aren't completely comfortable installing Windows on a bare machine, you should avoid this process. Find a friend to help you if you need it.

OK, so you're determined to dual boot. Here's how to do it.

1. Repartition - You need to make two partitions on your hard drive. One for Vista, one for XP. The Vista install DVD includes an app called DiskPart that lets you do this, or try GParted, which is a little friendlier but requires a little more effort on your part. Split your hard drive into two chunks, and make sure each is big enough for each OS (at least 20GB). Format the partition as NTFS. You can also use a second hard drive if you're on a desktop.

2. Check Your BIOS - If you're using a SATA hard drive (the standard for a couple of years now), you'll need to tweak your BIOS so XP, which came out well before SATA did, can see it. Just go into your computer's setup app and hunt around for the options for your hard drive, often under "AHCI." You want "compatibility," "AHCI off," or "IDE emulation" mode... something along those lines. Don't worry, this won't impact Vista at all.

3. Boot from an XP Disc - Now you can just follow the usual installation procedure. Just make sure you're installing on the correct drive: Vista will be on the C drive. Your new partition will be E, F, or another drive letter.

4. Repair the MBR - Installing XP after Vista prevents Vista from loading properly because it overwrites a critical file. Repair the Master Boot Record by booting from a Vista DVD and selecting "Repair your computer," then "Startup Repair."

5. Install a Boot Manager - After all this, you'll boot into Vista. You now need a boot manager to deal with the two OSes. Install EasyBCD (download at that link), run it, and click "Add/Remove Entries." Change the drive to whatever you used in step 3, and change its type to "Windows NT/2k/XP/2k3." Click Add Entry then Save. Any other boot manager will work, but EasyBCD is free.

When you reboot you'll now get to choose which OS to go into.

Good luck! (If you need more help, just search the web for "dual boot Vista XP" and you'll find even more tutorials. Everyone's instructions are a little different, so keep that in mind.)