I don't think the Touch will handle all of your requests. It is a closed system, on a smaller resolution screen. Music & Video playback should be superior, because of smaller resolution it doesn't have to work as hard. For browsing I find the resolution too limited.

The Nokia Tablet series have a higher resolution screen and you can install a mix of applications. I've done a fair bit with my N800 and it is a very capable device. For video you will have to recode or optimize the clips, pretty much. Actually same goes for iPod. The N810 gets the bonus keyboard and GPS (with slow GPS lock at this time). N810 > $400. N800~ $200.

My personal vote is for the IT series. But then, like many here, I'm biased due to the fact that I'm an IT user.