I have a question:
Is there a function, class or whatsoever that, when you have any file with any extension, opens the program which is related to that extension?

In other words, when a user selects an .xls-file and clicks on the open button, the program will automatically open Excel. And this for all the extensions. Maybe using the windows setttings which relates the extensions to specific programs.(Explorer->Map Options->File Types)

Please help me with this one