I thought I had a good idea as to how to not have any downtime on my very busy HTPC when switching from Vista to "W7".
The Vista / XP HD is messed up with Visa on a Logical partition and XP on a primary partition. Not good as I have started getting failures to resume from hibernation. As an OS reinstall was my best approach to this problem and "W7" is wanted for many reasons, I decided to move to "W7".
I was stalling as my idea was to wipe the system HD and repatriation correctly with primary partitions only. This approach would not allow going back to Vista if I messed up the install.
Then I came up with the idea of unplugging the old system HD and plugging in a new HD. The thought was that unplugging the new HD and plugging back in the previous Vista / XP would allow me to go back and forth.
I have installed "W7" on the new HD, messed up the network selection so I cannot see my other computers, shut "W7" down and removed it's HD.
I plugged in the old Vista / XP system drive and after a BIOS reordering of the boot order am back up on Vista.
I have discovered what appears to be "W7" boot files on one of my HDTV Video HDs, looking at Disk Management, it is Drive 0.
I think that I want to plug the new "W7" HD in so that it is Drive 0 at some point, the HDTV Video HD can be reformatted to remove the "W7" boot files on it.
I think that disconnecting the Vista / XP HD and plugging in the "W7" HD selecting Drive 0 as the first disk drive will allow me to go back to "W7" again.
But I think there is a better way to get ready to switch to "W7" while still allowing me to use the old Vista / XP until then. I do have DualBootPRO installed on XP, but not Vista.
When "W7" is stable with all my HTPC software working properly, the Vista / XP drive will no be used on my HTPC. (Note, I can have both system HDs installed at the same time.)