Delphi 7 will not work with Vista. I also tried for a while. Then found that the official statement from Borland is that it won't work.

However, what you may want to try is install Delphi outside of program files.
The problem is that Delphi 7 is unable to change files with the program files tree.

I didn't bother to try and instead installed Delphi 2006 and now just purchased and installed Delphi 2007.