I’ve recently put a Flash-banner on my site (Episerver 6). Now I’m trying to find a way to put an alternate JPEG/PNG image in the place of this banner if the user has no Adobe Flash installed or activated. As is now there’s just this annoying gray square telling me to get a Flash-player when I turn it off.
Your question isn't directly related to EPiServer 6. I'd suggest posting your question to Stack Overflow in order to get more visibility.