I'm kind of skeptical right now...
I use 1gb myself, but, who is to say that memory will not be modified to work much much harder and faster, with less? I know right now its not possible, but it is however, probable.
Of course, I don't own a lot of stocks, nor do I have a large cash cow. I budget my money, and in this sense, I stay skeptical about expensive purchases until I know it can prove itself... by that time, it is a fraction of the cost. For what I do, maybe 1gb is enough. If I were to go into graphic design or such, I would head upwards in memory... until then, I'm silently waiting...