Macs have a lot of substance. The stacks, among various other things that are in Leopard are nice to use. I bet we see them ported over to Linux/Windows in no time. I have used this before. While it was nice to use. It also takes over your PC. So if you ever want to remove it you are going to be in for a battle between XP and Flyakite. Because they both want control of your system. I finally had to do a format and re-install to get rid of it.