From what I have read, MS will be releasing Avalon for XP at the same time as Longhorn is released. Longhorn will have its "advanced search" technology, although it will not be powered by WinFS (which leads me to believe WinFS was pretty much worthless.)
Windows XP will still have the Luna interface, just powered by Avalon. You will still have to buy Longhorn to get the new Windows interface (is it called Glass or Aero, I can't keep track.) Of course, having played around with the Beta for Longhorn you're better off just sticking with XP if you really really have to go with Windows.
Currently, Tiger will still kick ass. I'm not really caring much about Spotlight, but XCode 2, Automator, and CoreVideo look worth the upgrade. Dashboard is spiffy too.
Windows XP will still have the Luna interface, just powered by Avalon. You will still have to buy Longhorn to get the new Windows interface (is it called Glass or Aero, I can't keep track.) Of course, having played around with the Beta for Longhorn you're better off just sticking with XP if you really really have to go with Windows.
Currently, Tiger will still kick ass. I'm not really caring much about Spotlight, but XCode 2, Automator, and CoreVideo look worth the upgrade. Dashboard is spiffy too.