[G4] Problem with Target mode

[Robert C. Buitron]

I have a MDD 1.25 GHz, 800/400 firewire, 2GB RAM, 4 internal SATA HDs, 
PCI 4-channel SATA card adapter, and a Sonnet Allegro PCI firewire card.

I recently purchased a G5 and tried to use the Migration utility to copy 
files from the G4 to the G5. The G5 has only 800 firewire. When I 
connect the two computers, whether through the 800, 400, or 800-400 
connectors, my G4 shuts down before reaching target mode.

Does anyone have a solution to this problem or another easy method of 
transferring files and apps (without having to go one by one with the apps)?

On the same question, where do I find all my email (I use Thunderbird) 
and bookmarks on the G4 and how do I copy that data to the G5?

Thanks!
Rob