Hi ... Are you saying you had 2 separate hard drive each having its own OS ( XP , Vista ) You were having MBR problems because you remove Vista and had to use third party software to get your system working again ?
I have 5 hard drives all connected , 3 have its own OS ( XP pro , Vista and W7 ) I can boot anyone of these from within the bios setting . Not once do I have any problems loading any of them . I can even remove any of the 3 OS drives and still be able to load the other 2 without any problems . I do all my changes within the bios setting ...
Yes. Let me explain in more detail. Originally I had Windows XP Professional running on Hard Drive (HD) A. Then I bought a 1 TB WD Caviar Black HD B, hoping to install multiple boot on the new HD. I connected both HDs A and B on the same SATA (II) cable to the motherboard. Then I partitioned HD B to several partitions. I installed Vista 64 bit on HD B Partition 1. However, since HD A is also connected, and in the BIOS setup was the first boot device, Vista actually changed the MBR of HD A, and added the Vista bootloader starting from Sector 1 (The MBR occupies Sector 0 of HD A).
If you installed the OSs separately on different HDs (i.e., not connecting another old HD having an OS when you install a new OS on the new HD), you will not have this problem. And yes, you can easily change the BIOS setting to boot from any bootable HD.