I've had good and bad experiences with different apple "genii". One time I needed to replace the little detachable extension cord segment that goes from the power adapter to the wall outlet and the guy at the palo alto store was hostile to me and flat out refused to give me a part number or any useful information (other than to suggest I purchase a whole new $100 power adapter). I eventually found someone on craigslist who was willing to sell me theirs for $15. But another time when my GPU failed a guy at the emeryville store saw to it that I was sent a new powerbook by overnight delivery.