curtain model

[Hermoor]

I don't know if this will be of some use for you. But in blender there is a wave modifier. Basically you just cut up a plane then put the wavemodifier on it. The plane will now behave like a wave...which is kind of like how a windy piece of cloth behaves. Then there is of course also the inbuilt wind physic simulator. I'm sure there is some way to bake the physics of the cloth into an animation.

Check it out:
http://www.youtube.com/watch?v=FBcg4SuAwZ0