I stick to 1-platter drives in my netbook, backup, and PC. Why? Because they run cooler, quieter, and faster. Your data is also a bit safer. Personally, I don't need 750GB in my netbook, but I could see some people wanting it in high-end notebooks. Let's face it - it's mostly for people with lots of video cough porn cough.
Confucius say, "Wife who put husband in doghouse soon find him in cathouse."