I've had this problem in Windows and OS X. For me, it has had nothing to do with the machine, and more to do with my ineptitude. Sometimes I drag more than one finger across the trackpad, or don't dry my hands off completely after washing them. iBook, MacBook, even PC notebooks; it's just a track/touchpad thing.
Multiple fingers or moisture really screwed around with the trackpad. If this isn't your problem I don't really know what to tell you.. I suppose there is a chance it could be hardware related (odd since it doesn't seem to occur in OS X), but even if it were I doubt AppleCare would cover problems that only happen in Windows.