I've had the standard alarm replaced twice by Toyota in the 14 months I've owned the car:(
It cost approx £110 the first time but failed within 6 months! They tried to charge me the same again until I pointed out that it should be under warranty.
The fobs are a bloody liability in that they frequently cease to work, effectively locking you out of the car:eek:
I have a diskloc which I regard as a better deterrent so I can't be bothered to upgrade.
The slider is definitely for enabling/disabling the internal sensors, these should be checked regularly as they can fail although the locking system will still function.