crazy emergency install that flopped drive letters

[FireBrick]

This is the weirdest thing.
Wife's computer wouldn't work
She had XP Pro.

I tried Repair, no joy
I tried fixing it via Safe Mode, no joy.

it would run in Safe Mode but in Normal mode, no joy.
I tired restore points, they wouldn't work even though I had scheduled
restore points once a day.

Trying to restore just froze and couldn't select a restore point.

Out of Desperation, I installed Vista Premium which is mine from my
computer.
That worked, sort of.
For some reason, D: which had lots of saved pictures and important files is
now called C:
C:, which was the OS XP installation location is D:

It's like they flopped during the Vista install.

And I'm expecting any moment to tell me that the Vista I installed is
already installed on a different computer. (this one that I'm writing this
on)

So can I fix the anomaly of c and d being reversed?
Can I just pay the fee for the second computer to have vista?

I'm in the process of again backing up those files to a outboard terra byte
drive for safety.
So I could, if I had to, format c&d and reinstall

Anybody have an idea of my best approach.

please and thank you

 

[DL]

It would require a purchase of Vista in order to run it legally on your
other PC
Are they two seperate drives or partitions of a single drive?

 

[FireBrick]

More than willing to purchase, in fact I already have it on order.

It was an emergency install to save files, data, etc.

and yes they were two different hard drives both sata.
Originally C was for Windows only with all data and programs installed to D.

 

[DL]

When installing a new o/s to a system with multiple hd's & card readers, its
often prudent to disconnect all other drives/readers, leaving only the
single hd & a single cd/dvd drive (You only need to disconnect the pwr cords
to the drives) That ensures a C drive installation