That's a really vague question. I hope you aren't trying to troll.
What do you want the various platforms for?
What kind of budget do you have?
What kind of battery life are you wanting?
What would you look at using the platform for?
Right now it's a shot in the dark.
You may want a 3g netbook because you are often on the road for business and need long battery life or prefer something lightweight and don't do anything major with it.
I really don't see how you can compare the iPod touch to the other two.
In my mind MP3 player vs Netbook/Notebook/PC the later will always win.