When is Flash not an appropriate solution?
Flash is like web design candy - as good as it tastes and looks you shouldn’t let it serve as the main course on your web site.
Over at Wake Up Later they’ve written a nice guide titled 6 Places that Flash Does Not Belong. I couldn’t agree more with their choices.
To summarize, you should generally never look to a Flash solution to replace something you could do with a straight-up HTML/JavaScript solution. You might have a hard time convincing your clients that a plain-text menu is going to perform better than the Flash-y, animated drop-down that plays sounds, but it’s really for the best.