Lego, Tinker toys, etc are indeed excellent gifts. For the somewhat older child, I highly recommend the electronic snap kits to show them the magic of electricity without the soldering.

Windows 7 is well worth the upgrade. We're a Mac family with one Windows machine, and my kids love Win7. I keep some old software dev stuff in an XP VM environment that works on either Win7 or the Mac, and I simply keep the TCP/IP ports disabled so virii and other nasties are no problem. There's no reason for me to migrate this crusty, old stuff to Win7, and the VM works dandy.

JPL is in the process of trying to decide where to send probes next. Both Uranus and Neptune are on the table:

http://futureplanets.blogspot.com/2009/05/minimalistic-uranus-orbiter.html
http://futureplanets.blogspot.com/2009/08/white-paper-argo-mission-to-neptune.html

Realistically, neither of these will occur. Not enough money to persue these along with all the Moon, Mars, Jupiter and Titan probes that have priority.