How do I format my HD that has my old OS on it, reciving error

[paulsapio]

I installed windows 7 on my computer and have windows Vista also installed on one of my other hds. When i start my computer I get the option to Boot 7 or Vista "duel boot" I would like to remove the vista OS. When I try to format the HD that only has vista installed on it I recive "windows was unable to complete the format. Anyone have any ideas on how to fix this?

 

[SIW2]

Post a screenshot of disk mgmt window.

 

[paulsapio]

(D is the disk I am trying to format

http://i129.photobucket.com/albums/p204/paulsapio/Capture.png

 

[paulsapio]

sorry the D drive is the Drive I am trying to format.

 

[gregrocker]

Mark Win7 partition Active: Partition - Mark as Active

Power down to unplug Vista HD, plug its data cable into Win7 HD so it becomes Disk0, set Win7 HD first HD to boot in BIOS setup.

Now boot into the Win7 DVD or System Repair Disk to run Startup Repair 3 Separate Times until Win7 starts on its own and holds the System Active flags on its partition.

Now you can power down to plug back in the Vista HD, boot into Win7, open an Elevated Command Prompt to run Diskpart Clean Command on Vista HD, repartition in Disk Mgmt.