Moving Outlook 2003 pst file to Outlook 2007 file

Hello,
I have not been able to successfully move my Outlook 2003 .pst file over to Outlook 2007. What I did was close Outlook 2003 on my Windows XP machine and went to the location of the .pst file. I then burned that .pst to DVD (since it was so big). I put the DVD in the Vista machine with Outlook 2007 on it and tried to import it and get the error “Outlook.pst is not a personal folders file.” It is located in the same folder as the original 2007 .pst file yet it is renamed. What am I doing incorrect?? Please help.
Miya