In XP I can modify the file types for xls and xlsx for opeing multiple
occurances of Excel.

In vista is has been dumbed down to not include the ability to edit file
types. I have been told this is a regedit of sorts, does anyone know where I
would do this?

I frequently use large and multiple spreadsheets and in XP this is a
wonderful feature but I have not been able to figure this out in Vista.

Thanks in advance.