As far as I know, all current laptops and all announced laptops are based on the 754 socket. For the time being, there will only be a minor difference in preformance. Unless you are planning on waiting more then 6 months and are planning to get a laptop that "might" not be very portable (or probably 9 months or more for the 939 mobilew units). I would not worry about it.
You can't buy future technology. All you can do is buy when you need the unit and buy the one that at the time best meets your needs. Because no matter how long you wait, there will always be some new cool technolgy just a few more months away.