Mac OS X only: If you need to transfer very large files from one Mac to another, instead of waiting for the copy to crawl over the network, turn one Mac into a FireWire drive using what's called Target Disk Mode. Here's what you do: shut down one Mac and connect it via FireWire cable directly to another. Then, hold down the T key and start it up again. The Mac will show up as an external hard drive on the other Mac's desktop, and you can quickly copy files to it like any other drive. Alternately, from System Prefernces, under Startup Disk you can hit the "Target Disk Mode" button.