Thanks so much for the replies! Sorry it's taken me so long to come back and check! Prathapml - Thank you, that does work! I was kind of hoping to be able to just open any mp3 though (Rather than one specific mp3), but that'll certainly work if that's not possible. Thanks! Yzöwl - That looks really good, it looks like it would do exactly what I want, but when I went into regedit I couldn't find the folders you have - There's no .mp3 or mp3file folders in my 'Classes' folder... I'm using Windows XP, if that makes a difference. Sorry, I'm really no expert at these things - The main reason I'm doing this rather than just opening the two programs seperately is to learn more about what's possible, but it unfortunately means I need step by step kind of instructions to really understand : \ Gunsmokingman - That looks really good too! I'm not sure if I have VBS though, that's Visual Basic isn't it? Unless there's something that comes with windows to run that I'm afraid I don't have it... Thanks again for all the help, it's really great of you to take the time! Sorry I need to ask all these extra questions...