Hi Geoff
I'm not aware of any quality 1G RAM chips here in the UK for less than about £200. You might be able to find budget RAM, but many believe this causes problems, so it's probably best to stick with reliable stuff - Kingston or Crucial. Check out the Crucial site - there will be links to your machine. Find out which RAM to use at the Apple site, or in your system profiler.
I'm not sure if you can install a faster drive in the iBook. You may have to go with an external Firewire drive, which should let you run more tracks but will mean you're not as portable. They're reasonably quiet and you could site them away from your machine.
Copying your data would simply be a matter of dragging and dropping. You can keep all your applications on the internal drive, but just have your audio files/sessions on the Firewire drive.