How to rotate a selection?

PS CS2 Win XP

I'd like to make a 'diamond-shaped' selection. Can't figure out how. The actual shape I'd like is just a plane square but one slightly rotated--maybe 15 degrees. Can't do this with marquee selection because once I make the selection and use Free Transform it starts to rotate part of the image. I want to make the selection--rotate it--and then have it select part of the image.

How do you do this in PS CS2?

Thx. for any help.

Jane

Select>Transform Selection or right click inside the marquee to get it.

or Alt+S+T