According to users going and complaining to Apple concerning the "whine" issue that has plagued first generation MacBook Pro users, Apple seems to have traced the problem down to faulty logic board problems.
Users are saying that Apple will supposedly replace the faulty logic board (covered under warranty) and that the new board requires Mac OS X 10.4.6, not the Mac OS X 10.4.5 installation that the Mac shipped with. As for now, this is all considered rumor and speculation as Apple has not made any official word on the problem.