I hope this posting and the movie will help some people who (like me) always wondered how an SSD might perform on FireWire 400. (I don't want to open the iMac if it is not really necessary) Getting better access and seek times is the goal. The throughput of ATA/66 or ATA/100 isn't much faster anyway so FireWire might be a valid option to get at least one of the benefits of an SSD. I've made this test on a Mac Mini 2011 to get pure FireWire performance without possible limitations of the FireWire controller in some older Macs (if there are any). The system on the external SSD is identical to the system on my internal SSD so you can get a rough idea how much of the performance is lost. The drive is the cheapest 128GB SSD that I could get (an Intenso 3812430 SSD for just 50,– EUR) - the FW case is from a Lacie D2 Quadra. Keep in mind that this is Yosemite, Leopard is much more lightweight and should boot much faster. I'll post another video how it performs as the external drive via FW400 on an iMac G4 800 once it arrived there (the drive is currently on its way to my mother in another city. XBench FireWire 800 results: I forgot to measure the drive with FW400 before I shipped it :-/ I'll post another screenshot comparing the performance of the SSD @FW400 ves internal iMac drive in some days.