I have a hard drive that has the C: as the logical with Vista on it and the D: drive as primary. How can I switch it so C: is primary and I can format D:
A program like Partition Magic will be of great use to you.
Also Acronis has a good partition program.
I would also google: Free disk partition software, here to you might find something of use to you.
I personally find Acronis software to currently be of more use to me.