If you absolutely must do a Flash intro, check out the way the Effie Awards site
does theirs. Why? Because visitors aren't forced into an either/or situation. The home page's top half features a light-hearted Flash cartoon with amusing audio, while the bottom half is a nice plain HTML page with navigation links to the stuff visitors want to access.
Instead of loathing the site for forcing me to waaaaait through their Flash intro (or click on "skip intro" and waaaaait for it to work), I got the best of both worlds. A fun little movie and the links I needed to act on. Funny thing -- I actually sat there and enjoyed the movie before clicking on to the information I orginally came to the site to get. If they'd forced me to see it, I would have sat there and fumed. Instead I sat there, voluntarily watching, and enjoyed myself. Way to go Effies!