make windows 7 c: drive?

#1
I have Vista loaded on Physical C: Drive and Win7 loaded on Physical E: Drive. I want to make Win7 the C: drive and Vista any other drive letter. I know my boot info is currently on C: with Vista and I do dual boot and it works fine. I would still like to dual boot after I make the changes, is it possible?
 

Terry60

Knows where his towel is.
Staff member
#2
Hi Mrolph, welcome to NST.
You can't change the drive letter of a Windows OS after it's installed.
(you can change it back to the original letter if it accidentally gets altered, but in that case you need to, because the change away from the installation letter prevents the OS from working)
You can however, generally force a new install to adopt C:\ as the OS drive letter.
The general rule is
Boot the installation DVD and install to an empty partition - the OS is C:\
Run setup.exe from an existing OS to install a new OS - the new OS is the 1st letter unused by the running OS.
Disk letters are not physical entities like disk labels. They are just registry entries in the running OS, and as such, they need bear no resemblance from one OS to another.
It's perfectly normal for Vista to be C: in its own mind, but for W7 to see it as X:

It's far safer for any multi-boot OS which can see (and access) other OSs, to regard itself as C:
This is because 3rd party software (notably anything written by Adobe) can often be very poorly written, and insist on putting some of it's files on C: even when you tell it to install elsewhere. You can see the confusion (and unpredicably consequences) of having Identical 3rd party installs on 2 systems, which have both put files on the same partition.
 
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#3
You can't change the drive letter of a Windows OS after it's installed.
(you can change it back to the original letter if it accidentally gets altered, but in that case you need to, because the change away from the installation letter prevents the OS from working)
Technically, you can change it (at least in W7), but as Terry said, it will mess up the OS because the OS is looking for all its system files in say the C: partition (or whatever drive letter it is currently), and can't find them, because the drive letter's been changed. It wont mess up your boot, per se, but it will mess up the OS, and you'll need to either change the drive letter back (from the command prompt, booted from the W7 dvd), or reinstall it.