Dual boot appears OK but Drive C is the same on both OS's


Seems like my issue is less common than most. Dual boot between Windows 7 (64) and XP professional was no big deal thanks to EasyBCD. I thought everything was OK until I saw that Drive C on the secondary boot was the same drive as the Primary Boot (Windows 7).

It's hard to believe that XP runs OK like that. I can save a file on Drive C in Windows XP and then see the same file on Windows 7 drive C.

Windows XP is running on drive H.( Yes, I have a ton of "removeable drives" that pushed the second partition up to drive H.)

I've tried telling EasyBCD that Windows XP is on drive H hoping that it would appear as drive C on Windows XP. I guess I could run it this way but sooner or later I think it's going to cause a problem not to mention how confusing it looks.

Does any one know how to re-letter drives under Windows XP. Administrator tools can not make these changes since apparently both drives are considered system drives. (and that is the only thing that makes sense)


It's getting interesting but I think I made it worse. I was able to actually see boot.ini on Windows XP. Windows XP kept it hidden even though I set it to read hidden and system files. I used the old DOS attrib command to remove the hidden attribute and then changed rdisk(0) to rdisk(1). That didn't work so I'm unable to get back to Windows XP.
So I tried editing it from Windows 7 again using the attrib command to get access to it. After making another attempt at editing it, Windows 7 said it couldn't save it even though I'm the administrator. Very frustrating.

Not sure that to try next...
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Drive C: on both systems is perfectly normal. Letters are not static like disks are, they are determined by each booted OS independently of one another.
Thanks for your reply. In this case Drive C on both partitions is the same Drive C. I don't think it would be long before I start writing on wrong drive. I would rather that Windows 7's Drive C be hidden from Windows XP.

Many years ago I used Boot Magic from Drive Image. It also provided Dual Boot and both OS's had a Drive C. Fortunatly, they were on different partitions.

I'm still trying to accomplish the same thing.
Windows historically, set disk letters dynamically at boot, in a specific order (Disk0 Partition1 as C, (1,1) as D, (0,2) as E, (0,3) as F etc till all the Disk0 had been lettered then back to (1,2) as G etc.
With XP, the stealing of D when a new HDD was installed no longer happened, and Disk Management gave the ability to set letters according to user preference, (except for drives with system ,boot or page flags).
From XP onwards though, unless you specifically set the letters yourself (which creates a registry entry to ensure that that partition/CD-ROM/Flash-drive always gets that letter when detected), the letters are still dynamically set as the system boots.

As regards the letter assigned to the OS, generally speaking, the rule is

Install an OS from a running system by clicking on setup.exe on the installation disk and the new OS will take the next available letter, unused by the running system. (i.e not C:\)
Install an OS by booting the Installation CD and it will use C:\ as the OS partition letter.
Once the install completes this is set in stone. You cannot change the OS letter without breaking the OS (it has thousands of registry entries for its drivers etc., all telling it to look for that letter)

Note the generally above though.
I happen to know from experience that XP, installed from the booted CD can still use notC:\ if it detects another partition with Windows installed. (This doesn't seem to be the case with Vista and W7).

The only problem of the OS not being C:\ is that 3rd party apps (Adobe notably) will try to put common files on C:\ even if you instruct the install to put the app on D:\.
If C:\ is a different OS with it's own apps then you'll get the installs scrambled together with unpredictable results.
This only happens though if the running OS can see a C:\ drive.

btw. Do you use system restore ?

With a Vista/XP dual boot, XP will destroy Vista's restore points unless you've got the MS registry hack to hide the Vista drives, or you use something like HnS to do it dynamically at boot. (the MS hack doesn't work for everyone, hence HnS)

One or other technique will prevent both system restore and 3rd party app clashes.
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Thank you Terry for your thoughtful answer. I've done some sole searching on what I'm trying to accomplish by creating a dual boot. I have some legacy programs including AutoCAD 2002 that won't run on Windows 7 so I either have to dump Windows 7 (and I really do like it) or maybe a better idea would be to keep my old machine with Windows XP running on VNC or a KVM. I may also try to create a bootable external Windows XP drive but for now the Dual Boot option is going to be shelved. I was an interesting experiment none the less.
If you have 2 HDDs, it's easy to have a W7/XP dual-boot with both OSs as C: (just install each one with the other disconnected).
If you must have them both on one HDD, and both C:, then either install XP first and then W7 (both from booted installation disks), or use a partition manager to set the hide bit on the first OS partition while you install the second.
As I said before, there's no problem with running an OS as notC: provided you make sure it can't see another OS called C:, and in the case of XP you don't want it to see W7 anyway because of the restore point problem.
I didn't mean to give you the impression that it's a difficult problem - just the opposite. It's easy to get it working. I've been running like that for years.
I was just warning you of the potential problems which could hurt you in future if you don't realize they exist. They're very easy to prevent.
Thanks again Terry. I did a normal XP install and then I installed Windows 7 as an image. I had put a couple of weeks into the Windows 7 installation and didn't want to install it from scratch.

I think an ideal situation for me would be to have a full Windows XP system installed on a bootable USB hard drive. They are selling now for about $50 or $60 in the size I need. My computer allows for USB boots so I think it's possible.

I already have a Windows 7 bootable USB hard drive from which I installed the image.
Both drives would be a single partition.

The dual internal HD solution sounds good too.

I really appriciate your help with this but before I restore the image again, I'm going to try to see if AutoCAD 2002 and Visual C++ 6.0 installs despite the warnings to the contrary. If it does, all this will be unnecessary.