Every once in a while you get a free computer. In my case, it was aSnow White iMac witha G3 processor and, fortunately enough, I had a use for it. I use myold Sage iMac G3 as adigital jukebox that outputs to my home stereo.
The Show White has a stronger processor (600 MHz vs. 450 MHz) and alarger hard drive (40 GB vs. 20 GB), so it is a little bit of anupgrade.
How to migrate everything to the new iMac? The Snow White does notpossess a DVD drive, how would I install Mac OS X 10.4 Tiger on it (theinstallation disc requires a DVD drive)?
Simple.
Old Tech
What I had on my side was a FireWire 400 cable and good old Target Disk Mode. Target Disk Mode makes thehard drive in your target Mac (in this case, my Snow White iMac)accessible from another Mac with FireWire (in this case, my PowerBookG4, which has a DVD drive and a FireWire port, running Mac OS X 10.5 Leopard).
G3 iMac in Target Disk Mode.
The process begins with both computers off: Make sure any FireWiredevices are disconnected and then connect the two Macs using a FireWirecable. I started up the Snow White and held down the T key onthe keyboard to enable Target Disk Mode, and the Snow White booted inDisk Mode.
I placed my Tiger install disc in the PowerBook's DVD drive.
Wait a minute, Sparky! Check to make sure that your targetcomputer's (Snow White) hard drive appears on the desktop of thecomputer with the installation disk in it (PowerBook G4). If it's notthere, make sure that you have the FireWire cable attached to bothcomputers and that the target computer's screen has the Target DiskMode symbol dancing around a blue screen.
Now you can click on the Install button on the Tiger installdisc.
The install disc will restart your host computer (PowerBook G4) andstart the installation process. At one point, you will be prompted tochoose the disk on which to install OS X. You want to pick thetarget computer's hard drive (Snow White), not the host computer'sdrive.
Go off and learn Finnish or something.
When the installation is finished, shut down both computers. Idisconnected the FireWire cable from the host computer (in my case, thePowerBook G4) and, while the Snow White iMac started the welcome spiel,I attached the FireWire cable to my old Sage iMac and started it up inTarget Disk Mode.
When the computer with the fresh OS X installation asks if you wantto transfer your settings from another Mac, you are all set!
Sayonara, FireWire
Unfortunately, FireWire is going the way of the dinosaur. What withUSB 3.0 looming on the horizon and Apple making it's laptops moreenergy efficient* and more compact, I'm afraid that FireWire will"whither on the vice".
Still, in this application, it serves a real need. Besides, all ofthe computers in this situation are equipped with USB 1.0 and 1.1.Rather slow for this sort of data transfer. 
