Disk drives letters
 

I have this problem : I replace my d: hard disk with a new WD 120GB hard
disk which I want to use as drive c:
I copied my original drive c: to the new hard disk and booted from the new
master hard drive the 120GB one.
Windows started normally but drive c: is my old drive ,and the new hard disk
is shown as d:.
I tried to format the old hard disk and afterwards windows reported that it
can not log me in.
After that I copied everything to my old drive and system restarted showing
the old slave hard disk as drive c:.
I tried uninstalling the primary ide controller but the problem remains.
Any help ?