I need a device to manage all of my multimedia, do internet, and use programs, but I don't know where to begin?

I want a device that I can listen to music, watch videos, browse the internet, use programs and applications seamlessly, and it needs to be portable. I don't want anything cheap like a Coby Kyros or Toshiba Mini, but I don't want anything ridiculously expensive like a MacBook Air or Asus Eee Slate. Please feel free to add products that have not been released.