Thought I'd post this in case someone else is trying to dual boot XP from a main and backup drive. Here's the scenario and what worked for me: When I upgraded my homemade computer a good while back, I installed a larger hard drive and a CD burner. Wanted to keep my existing older drive for backup purposes and the existing CD-ROM drive to save wear and tear on the burner drive. Since I only had 2 IDE drive connections on my mainboard, I installed a Promise Technologies add-in SCSI controller card with 2 more drive connections. Running my newer main hard drive on the first mainboard IDE connection and the CD-ROM drive on the second. Running the backup hard drive on the first SCSI card connection and the CD burner drive on the second one. (Arrived at this after having all kinds of XP boot problems with both hard drives on the mainboard IDE slots and the 2 CD drives on the add-in SCSI card slots.) I used the hard drive utilities that came with the new drive to mirror copy the XP Home installation and everything else from the newer drive to the older one. Complete bootable backup of my new drive for ultimate crash protection. (Note that I had initially upgraded from Win98 to XP at the same time as adding the new hardware, so for activation puposes it "knew" I wasn't trying to steal it. No major hardware changes detected.) Only dilemma I've had all this time was that if I wanted to test boot from the backup drive, I had to disconnect the spare drive from the SCSI card, disconnect the main drive from my primary IDE connection on the mainboard, and connect the spare directly to the IDE connection. After revisiting the issue recently, and wading through all the confusing info out there on the XP boot.ini lines, I found the solution. Please keep in mind that this works for MY configuration of drives as listed. In my case, there is only 1 partition on both the main and backup drives, and that is a major deal if you're trying this and have either drive with more than 1 partition. After much twiddling with the boot.ini lines, and way too many reboots, I ended up with this: [boot loader] timeout=5 default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS [operating systems] multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="XP on primary drive" /fastdetect multi(0)disk(0)rdisk(1)partition(1)\WINDOWS="XP on backup drive" /fastdetect C:\CMDCONS\BOOTSECT.DAT="Microsoft Windows Recovery Console" /cmdcons Explanation: "timeout" is for wait time in seconds during boot screen to select the Windows version to boot to. Make it whatever you want. "default" line is XP generic boot-to info, and points to my main C: drive installation. Nothing changed from original. LEAVE IT ALONE! (Overlook the fact that the "S" in "WINDOWS" is on a second line. Should not be. Some weird thing to do with this posting that I can't seem to edit differently.) First line under "operating systems" beginning with "multi" points to the main C: drive XP installation (changed the wording to display on the boot screen to "XP on primary drive" for ease of use). DON'T CHANGE ANYTHING ELSE IN THIS LINE! Second line under "operating systems" (THAT I HAD TO ADD) beginning with "multi" points to the XP installation on the D: backup drive connected to the SCSI add-in card. Note the "1" instead of "0" for the "rdisk" value. Made the wording for boot screen display "XP on backup drive". (Note that this applies in my case where the Promise Technologies SCSI add-in card has it's own BIOS that displays after the main initial BIOS, and detects the drives connected to it. I've read that if this is not the case, the "multi" might need to read "scsi". You're on your own with that.) Note that if you have more than 1 partition on either drive in this scenario, you'd have to tell the "partition" value where to look for XP in the appropriate line corresponding to the hard drive. Note also that the last line under "operating systems" is for the MS Recovery Console normally available for Windows repair when booting from the XP install disk. I have Recovery Console installed on my hard drive so I don't have to use the CD if needed. Link included at the end of this for how to do. Leave it out altogether if you have not done this. When trying to boot to the backup drive with these boot.ini lines, it wouldn't boot when choosing the backup drive. Having to reboot and choose the primary drive to start. Final step was to change the boot device sequence in the BIOS. Ended up with first device as floppy, second device as IDE0 (main hard drive connected to mainboard), third device as SCSI (spare drive connected to add-in SCSI card). Voila! Since I had just recently mirror copied the new drive to the old drive, everything on the desktop looked identical. Indications that I had indeed booted to the spare drive was a lack of hard drive indicator light activity on the front of my machine (connected to the mainboard and not to the SCSI card). Another indication was one of the XP services, Generic Host... asking for permission to go out through my firewall, and permission to do so had already been given from the C: drive. It worked! No more fiddling with the drive cables if spare drive booting needed! IMPORTANT: All the desktop and start menu shortcuts still pointed to C: drive, so even though I had booted to and was "running" on the spare D: drive, the programs still referenced and launched from the C: drive. Meaning that if a catastrophic failure of the C: drive, they wouldn't launch. Merely a matter of changing where each shortcut points to by clicking "Properties" for the shortcut and changing the target from C: to D: Cool. For a test I made a Notepad document and made sure I saved it to the D: drive under My Documents, made a desktop shorcut to it and made sure it pointed to it on the D: drive. Now when I boot from the spare drive, I can tell instantly that it's the one I'm running on. Not there when booting to the C: drive. Way cool. To finish up, I copied the boot.ini lines from the one on the C: drive and replaced the ones in boot.ini for the D: drive. Not sure if this is necessary or not but it works. E-mail me if questions, or if you want to try the disk copy utility. I've tried disk copying software in the past to copy one drive to another with mixed, and lousy, results. This utility makes it a breeze to exactly mirror it, took about an hour for a 60Gb drive. Link for installing MS Recovery Console from your XP install CD to your hard drive. (Boot.ini line will be added automatically.) http://www.windows-help.net/whistler/howto-12.htm Boot.ini file can be easily edited by opening it with Notepad, or through Control Panel, System, Advanced, Startup & Recovery, Settings, Edit. Notepad is easier. Sorry for being long-winded, but I had previously found a simple explanation for how to do this difficult to come by. Again, only works as listed for my particular configuration. BE CAREFUL fiddling with boot.ini lines if you're a newbie. You can easily get into a non-boot situation! Should be relatively safe if you leave the line for "default" alone as well the first line under "operating systems". Hope this helps!