Until I see something definitive about the status of the faulty logic boards in the ibooks (G3), I would steer clear of them. However, I haven't seen the same reports on the G4 ibooks yet although the apple boards are beginning to "heat" up about it.
In anycase the machine isn't the only issue. There is OS X and XP. I use both, administer a network with the latter, it simply comes as a matter of choice and from what you want to do.
If it is games, go PC, definitely an edge. But there are many uses.
Both platforms have their good points and bad.
Peace