No mikel, some plugins add files to both folders...Take WGA and OGA for example, they put a .DLL in Plugins folder and also a extra file .XPT in Components so. If you want to know what files are added and where, before you install a new plugin into Firefox take a snapshot of your system with Installwatch, then install the plugin and then go back to installwatch and see what files were added where But ussually most plugins are a single .DLL file that goes in Plugins