My laptop came with V64 as well. My old computer is still dead, but I installed a fresh copy of Pegasus Mail 4.41 and it runs fine. (However, Vista is a PITA and getting more so with each 'upgrade'.) There are a couple of caveats. Vista refuses to recognize Pegasus as a "system mailer" is the largest, but it can mostly be worked around. There are other threads on this board that go into great detail on this problem, so I suggest you look around. Search for "Vista" and you should find them.
My laptop came with V64 as well.  My old computer is still dead, but I installed a fresh copy of Pegasus Mail 4.41 and it runs fine.  (However, Vista is a PITA and getting more so with each 'upgrade'.)  There are a couple of caveats.  Vista refuses to recognize Pegasus as a "system mailer" is the largest, but it can mostly be worked around.  There are other threads on this board that go  into great detail on this problem, so I suggest you look around.  Search for "Vista" and you should find them.