Might be interesting to find out from anyone with a US NC10 if the memory is actually running at 800Mhz.
There was a similar situation with a Vaio I once owned the Bios underutilised the available speed. The USA Sony site released a new Bios to rectify this but elsewhere in the world they never did.
Unfortunately trying to install a USA Bios on the same model elsewhere was rejected by the install software. It was a laborious process to graft the relevant parts to a Euro Bios file thus allowing the upgrade.
If the above is true then I hope Samsung is more friendly in this area.