Question: I bought a new HD (1 TB) which was my D drive. I want the new HD to be C drive and someone helped me to change that. Now my new HD is C drive but with 2 OS (Windows 7 and Vista). My old HD is now D drive also with Windows 7 on it. So now I have 3 OS on my PC. How can I delete Vista on drive C and the other Win 7 on drive D.

I only want the Windows 7 on the C drive. Windows 7 Ultimate must be my main and only OS. So..... When I delete the "Windows old" directory it should work fine or do I still have to do the boot ini thing? Where do I get this bcd?

Answer: 
Boot up the machine using a Linux LiveCD, such as Ubuntu. 

Then you should be able to edit the disk partitions with `gparted` and delete one. 
You can then create a new partition in the free space, or expand one of the other ones to fill it. 

The problem with using Disk Manager through Windows, is you may find it impossible to edit the disk that's currently in use.
If you want to delete vista then log in using windows 7 and go to run and type `msconfig`without quote. **System Configuration** windows will be open then see in **Boot**.

If there is vista present in the list then you can delete it. and after restart you can format your vista drive using cmd.

In case Vista is not present in System Configuration > Boot list then log on using Windows 7 and delete the partition which has windows vista then repair your startup using windows 7 bootable disk.