|arnaasak review the KISS principle [google it]|
you are making this way more complicated than it is.
You don't need partition magic at all when using MS products exclusively.
One internal drive or 4 internal drives, multiple partitions on a disk or all disks, makes no difference. It is all the same
You can't raid now so forget that path.
"I need to operate each separately" Of course. That is what a multiboot does.
Follow the instructions above once you have uninstalled Partition Magic. Boot magic will be removed from the mbr with the xp install. Then do the windows 7 repair and you will have your multiboot.
But for heavens sake backup everything you have on Win7 first.
Answers are only as good as the information you provide.
How to properly post a question: