I copied my Windows XP SP3 to the biger drive and throw out the old lazy and little drive from my system. I had have some problems but I get help and it works, see for more info: https://www.wilderssecurity.com/showthread.php?t=274737 After that I installed Windows 7 64 Pro eng on the other drive. I was surprised that I didn't get the usual dual boot menu with Windows 7 and The older Windows... I check the partition table with Partition Wizard and found out that I have Disc 0 on the drive with data, Disc 1 on the drive with Windows XP and Disc 2 on the drive with Windows7. When I boot it starts with WindowsXP but I can go to bios boot menu and boot from Disc 2 and I get Windows7 Well I can boot in Windows7 and edit boot with BCDEdit so that I get boot choice on screen I think. If I put the primery boot on Windows7 partition of course. But my question is should I and can I change the drive numbers so that my first OS Windows7 drive get number 0 and second OS WindowsXP driver gets number 1, or not?