Partitioning an Old Hard Drive for Clean Install

Hi,

I just did a clean install of Windows 7 on an older hard drive that I salvaged from an old pc.  I used the Dell provided Windows 7 DVD.

The old hard drive had just one partition, and before I even took it out of it's original pc, I did a simple delete of all files before putting it on the shelf for years.

Yesterday, I connected the old hard drive to my desktop, and noticed there was still one file in the partition.  I thought so what, performing a clean install with the Windows 7 DVD will ask about making a new partition, and will then erase the one file still on the hard drive.  To my surprise, the install didn't ask about deleting the old partition.  There were no 'active' delete buttons that I'm use to seeing when installing Windows from a Windows disk.  What showed up in the "Where do you want to install Windows"? pane was the Disk 0 320 GB (it also did not say 'unallocated' per usual.  The only active button was 'New', but I didn't want to create a new (second) partition.

The install went fine, and I am using the clean install as my new OS disk.  The reason I know that Windows just installed itself on the old disk without doing and deleting/partitioning, or any disk management is because that one file I mentioned above was still on the hard drive.

Should I redo the clean install?  If so, since Windows did not delete the old partition, should I do all that myself before redoing a clean install?  What tools should I use?

TIA