I've used limewire before on a different computer and it works great. On this computer I can dowload files and listen to them fine. I can also listen to them with other applications, but only when I first download the files. whenever I close and re-open limewire, the files aren't in my library anymore. They're still in my shared folder but they won't run in the other applications anymore. Please give me some suggestions I am using a Mac OS X

Compare the preferences between the two computers, including the Quicktime and iTunes prefs. Do post back and let others know which ones work best.

my other computer is a windows and i'm not used to using the program on mac

Ah! Did you find the LW OSX pref for "use iTunes"? The other way to map files to apps on OSX is to click once on the file from the hard drive, and use the Finder's File->Get Info command to see the options for "Open With" and setting defaults. I think iTunes also has an option in its prefs to be the default internet player.