Attempting to copy to the disk failed.

Help! I just bought a MacBook Pro. My other computer a iMac G5 is the computer my iPhone was originally synced with. I was successful moving my library to my MacBook - but now when I try to get my iphone to sync with the MacBook - I get "Attempting to copy to the disk failed. The required disk cannot be found." So here are my questions:

(1) Does this mean I cannot sync my iTunes purchases made on my iPhone to my laptop?

(2) Does this mean I'll have to transfer the iPhone iTunes to my original computer, then make disks so I can load them into my laptop?

(3) From what location should I purchase my iTunes music from (laptop, iMac or iPhone) in order to share it with all three locations?

Obviously, I have the brains of a shoelace re-tipper and would appreciate some guidance here. All the Google did was confuse me. Yikes!