The combination of Pocket FMS on an HTC HD2 stuck on the dash (all up cost: £400 for the hardware +£100 a year including monthly updates) and a Garmin 430 built into the dash is about as foolproof as anyone needs. Pocket FMS even gives you geolocated approach plates so you can fly perfect holds without all that wobbly stuff in the wind you do with an NDB hold. Then off down the proceedure following the GPS needle on the 430, make the 180, switch to the ILS and down the crossed needles you go, with the Pocket FMS giving reassuring aditional spatial awareness along the way.
So it's horses for courses, really.