I am trying to remember what I did.
This is my plan with the help of everyone.
I have seven hard drives on my pc under windows xp pro.
One of these drives have partitions. In some of those partitions I have installed six times windows xp pro.
At the present moment I think I have made my first mistake according to your considerations.
I have installed Windows 7.64 over STo (that's the letter I: in the old structure).
What can I do ? I think the best option is substitute the present systems disk. The present one is 1 TB. One of 1.50 TB possible would be fine. Or even 2 TB.
Make provisional partitions in the new disk and make certain the first installation goes to the C: partition in the new disk where the bcdedit.exe must be.
That will be my first system under windows 7 with the new boot. I have security copy of all about the c:\ at this moment.
This are by custom my installation letters : C: , D: , F: , I: , M: , N:
What I did ?
I have a dvd unit
I will connect to the mother board the system disk when install over C: . And the dvd.
Then install a second system on D:
Then connect the second hard drive. Select one with only one partition.
That occupies the letter E:
I will install then over the partition F:
Then connect the third hard drive to get the installation letter I:
Install in the system disk the fourth system.
(I suppose I can even restore an acronis security copy from the old pc hard drive with my retail version of xp)(but this is not necessary)(So I would install Windows 7.64bits in the fourth system)
Then connect a new hard drive to get the letter M:
And installs over the letter M: . There goes my main system.
And then installs over the letter N: in a new partition in the system disk.
I think this was I did with windows xp pro.
But I remember was not so simple. By any reason a system may be seen from other with a different letter I have to change.
And that is the case the kb223188 because initially was C: and in other system is another letter.
But this is not my present situation. Because I made the mistake to install over I: the new windows 7. And now is really C:
Possibly I can restore image copies and have security copies of the boot.ini.
But this is irrelevant with the plan to change the system disk to another more confortable.
Can I do this with windows 7 64 bits professional edition ?
Note : So many systems are the result of my little trauma with xp. At the present moment I have over 60 virtual machines under virtualbox. Possibly so many systems perfectly installed is not necessary, but i am very used to call M: my main system and I am not a programmer but have many scripts pointing to that letter.