Explorer.exe is the Windows shell, and is is always running. Iexplore.exe would be Internet Explorer. The way i've understood it, the Temporary Internet Files folder is only used by IE, not Firefox (I'm not sure though). Firefox keeps it's own stuff under Documents and Setting/Something/Someting. You can force Firefox to put all downloads into a folder of your choice, or alternatively (like it is by default), Firefox always asks you where you'd like to save the file.