why doesn't qif file open? system 10.4.11

I have system 10.4.11 on Intel Mac. My system profiler says I have version 7.6.4 Universal installed, though I can't actually find the application. I created qif files from my Quicken 2006 account, but they won't open. I use Fiorefox 3.6.28, but these files are in the finder. What should I do?