memory question

[Shahara9 at aol.com]

I presently have an icebook, two years old, and am eventually going to 
purchase either another 12" iBook, or perhaps a Powerbook, and am wondering 
if my extra 128 MB DIMM1/J12 SDRAM in this laptop can be used in either of 
the newer laptops.  Are the batteries similar?  I doubt between iBook and 
Powerbook, but older and new iBooks ?

Also, what benefit is there of purchasing the Apple Protection at the same 
time as the computer, rather than perhaps forgetting to do so in the future?
thanks alot
~shahara