Dual-Boot on 2 Hard Drives

I installed windows 7 on the larger hard drive,then installed windows XP on another drive,same computer,both drives are in sata ports 1 and 2,I have the bios set to AHCI,I had no problems with the install,but now it only boots the XP,it doesn't give me the option to what OS I want to boot from,and when Im up and running in XP,I can see the other drive using explore with everything I installed on it,but now I cant boot back up into windows 7,I tried to set a dual boot to be able to use both operating systems,what did I do wrong,thanks

so your saying to take one out,do the install until its completely done and it boots,then add the other HDD,do another install on that one with the other OS and everything should run fine after that,does this sound right?thanks

I did this on a computer we bought for work. It came pre-loaded with Vista but we wanted XP so we bought a 2nd hard drive, unplugged the Vista HDD and installed XP on the new HDD. As far as each install of the OS is concerned it was installed on C:. When we plugged the Vista HDD back in the computer still boots to XP by default but if we want Vista we press the F12key (or whatever the boot menu is for your bios) and choose the 2nd HDD. Make sure to hide the other OS's HDD from each install under "Computer Management" so the OS or you can't inadvertently affect the other OS. This worked fantastic for our uses since we want X 99% of the time and if we need vista it's a press of a button on boot.

I don't quite understand what you meant by "Make sure to hide the other OS's HDD from each install under "Computer Management" so the OS or you can't inadvertently affect the other OS." How and when to do you need to hide the other drive once it is configured the way you explained? As long as you select which HD to boot to, why does it matter?