Another good idea if one has the iBook or Powerbook is getting a spare Apple optical mouse in the briefcase for when out and about.
If you are used to using the right mouse button in Windows, you may want to look into a two button USB mouse (Logitech and Microsoft both have decent and cheap models). And if you have one, you can probably just use it. While you can use the one button mouse/trackpad just fine with Mac OSX, I've found the second button quite handy.
goates