It depends on how you distribute your AIR application.
An install-badge wpuld be very nice.
If its an AIR application you could add an install Adobe AIR badge.
If you distribute it locally you can get the permission from Adobe Inc. to distribute the AIR runtime with your app.
If its just an website it would be better to do it flash player.
umm.. may be your's is like acrobat.com kinda stuff.. which uses AIR.
Thank you so much!
I submitted my request to adobe to distribute Adobe runtime along with my AIR App.