Cannot view the movies I made on my camera and downloaded to my Vista PC

Which player do you play your downloaded video? Sometimes due to corruption in files, incompatible file format, or issue with the operating system, you might not be able to open some files. You can check the following part for the detailed information of them.

Source: What If the File isn't Compatible with QuickTime Player?

You should make it clear what format the video is and you find the compatible video player to open this file. You can try to get a universal video player which can support most video formats.

I assume you can view them in you camera, right? If not, the following solution will not help.

The .MOV Apple QuickTime format Panasonic uses for its camera movie clips cause problem on with viewing, as seen from several other problem posts here and the net.

Some computer use a Win 32Bit operating system, other better ones use a Win 64. It is hard to believe QuickTime would let you load a 64bit version into a 32bit OS, or vice versa. But who knows. Rather double clicking on te file name itself, open QuickTime, then go to File Open and Browse to the file and select it that was. If this doesn't work, go to QuickTime website and try their User Forums first to ask a question or find a thread talking about movie files not playing. Else, CONTACT website and ask question. Post any solution here for readers.