I like to switch between computers; I might prefer Mac OS X one minute, Linux the next, and Vista five minutes later. To make this work, I like to keep all my files in sync (sure, I could set up a file server at home, but I want this to work seamlessly if I leave the house). For my essential work files, I use Unison at the command prompt, and it works great. But I ran across SyncToy, which is a very fast, Windows-only program for syncing files. I started using it to mirror my photos and MP3s from my Mac to my PC, and I’m hooked.