Verify each by total size.  You could also disconenct the known D rive and hook it backup once the install is complete.

sorry forgot to mention its a laptop. and i am identifying them by the size, my smaller hard drive that used to be named D: is now named C:.

Maybe this picture can help clear things up. :)

http://i107.photobucket.com/albums/m300/bigballer044/help.jpg

The Black Circle is my Main HDD. (The bigger one)
The Yellow Circle is the Backup HDD. (The Smaller one)
See how the yellow one is labeled as C: to the left i need to get that to be D: and make the larger hard drive which is unlabeled to be labeled C:.

Ok so I got windows installed on the larger one and when i go to my computer it shows:

Backup (C:)
Local Disk (D:)

It did not automatically change to C after I installed. And when i try to install a program it always wants to install to C:........ I really need to fix this -_-.

Have you actaully looked inside the drives ti see where the Windows install is?  If it is truly on the D drive try this.

 

Go to Computer Managment>Disk Management and chnage the drive letter of C to something else.  Try X.  Now re-letter D to and X to D.  You will get some sort of warning message about changing the location of the Windows install.

 

I think that Windows just got "stupid" in this case.

Bigballer044

Did you even look at the link I posted?

 

Ron 

 

 

Yes, I did but it WONT let me select the option to change the drive letter......

I believe your issue revolvesa round the fact you chose the wrong drive when isnatlling the OS.  By default Windows will use C but your MBR could contain errors.

 

Disconnect the second Drive and reinstall Windows.

Disconnect the external drive and reinstall the OS.

It's a laptop -_-.

I have foudn out it is one hard drive with two partitons on it. And when I try to change the letter of the partition with the way specified in an earlier post i get an error message saying "Windows cannot modify the drive letter of your system volume or boot volume."