Alright, I got the DVico Momobay firewire-enclosure and a new 40 GByte 2.5 Drive.
Now, my old HD (20 GByte) is packed with valueable data to almost 100 %.
Can I take it out, install the new HD and all the Software, then put the old HD in the enclosure, plug in the Firewire and copy the data back onto the new HD?
Or do I need to make another back-up somewhere else? Due to the data-size this would constitute a serious problem, as all I have got here is my powerbook and this one drive.