How can I change which programs to open downloaded files with?

When I was downloading a song, I accidentally pressed Open with mozilla and ';Always Do this'; instead of Open with Itunes. I've tried to change it, but I'm not sure how. Please help me! I would very much like to be able always choose what programs to use when opening something.How can I change which programs to open downloaded files with?
Which download manager do you use? that would be helpful for answering.





For opening an already downloaded file in windows, just right click on that file go to Properties





There will be a change button against the program with which the file is currently associated click on that





Select Itunes from the list, if it is not present in the list then browse to its executable file and click on always use this program





click ok in open with dialog and click ok on the propertiesHow can I change which programs to open downloaded files with?
Right click the file and select open with. Then select the original program and turn on the always use box.
go to start menu, hit defaults, hit set default programs , chose itune, click set as default