Week, months, years it don't matter. What ever you buy for the forseeable future will be junk in a year because of the rule (Moore's law) that says computer power doubles every year or two. I assume you will have your notebook for longer then a few weeks or months. Famous notebook makers are starting to put desktop chips in their notebooks now. I went with a "off brand" cause just a month ago you couldn't buy a 2G notebook from somone like HP and now this month you can. In a year .09micron 4GHz machines will be out and in a year from that who knows?
IMO the two biggest factors keeping notebook speeds well short of desktops are drive speeds and video cards, memory does not make a spit in total relative speed compared to the other factors. Drive speed will always be less in a notebook because the drives need to be smaller and use less power hence a slower drive. I suppose someone could design a hoss vid card to slam in a notebook but I suspect the power and heat makes this impossible with current tech.
Sorry I'm not giving you the answer you were looking for but I don't think it really matters. Anytime you wait a month something better will be out or at least the price for existing products will be lower, either way you will always have a reason to wait. The question is how bad do you need a laptop and what could you be doing with one in the month you would be without one if you wait.
Give me fuel, give me fire, give me that which I desire.