Where should I place and backup my mp3s?

I like to play music directly off my laptop wirelessly to my stereo and speakers system using a music wireless device (Squeezebox).

I currently have 90 GB of mp3s. 60GB of music are in my Imac which I never really use to sit down to listen to music. 30GB are in my Macbook Pro. I would like to eventually mobe the music in the Imac to my Macbook. But this would take a lot of space on my Macbook.

I have been exploring options and scenarios, such as using one of these:

1. Get an Apple TV 160GB (dont have a TV)

2. Apple Time Capsule

3. Western Digital 1TB External Hard Drive (not wireless and I do move my laptop around the house so I cant be carrying the external hard drive)

4. Can I expand the capacity of my macbook pro? (currently 200GB)

5. Will using an external Hard drive of any kind create delay everytime I open Itunes?

6. Amazon sound cloud (needs internet connection always)

Not sure which way to go....

thanks!