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It should work. I took my 2002 ibook from 10.1 all the way to 10.4.11. I don't see any problem upgrading. In fact tiger ran better that that earlier versions.

Just be sure to back up your data before you upgrade... because sooner or later...
 
All of the iBooks ever made can support at least 10.3.9. Other than the very first one made, the G3's support up to 10.4.11, and the 933mhz+ G4 iBooks support up to 10.5.8 (with enough RAM).
 
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