I don't know if I can answer that question for you. I was someone who seemed to be an anti-2gb'er before. Since I have put it in my machine, I swear I notice a difference. But that can all be in my head.
My main reason for going with the 2gb was knowing that games out there (like Doom3 and HL2) were not starting to push the limits of 1gb gaming and I didn't want a machine that I would have to pay into down the road (I mean six months down the road, not a year or so). If I was going to invest in this system, I wanted all that I could in it. True - it is outdated already, but that is technology. But I don't regret the purchase.
If you love gaming in games like graphical RPGs, FPS, etc. The extra memory is probably not going to hurt. If you are strategy gaming... maybe you don't need it. But for the prices nowadays. It is pretty easy to slap in the other 1gb. Just run a program like CPU-Z and identify the exact model and specs of what you have in your system and then buy your upgrade. I could have gotten cheaper or better memory. I opted for the same model to ensure stability. I can work on desktops all the time - but I don't like to risk anything with my laptop. Especially considering the 1 week ship time both directions when needing assistance. So I take it a bit more conservative.