I have a 120GB one and it's "just right" for me right now.
The rest of the config is really good, the cpu in your setup is about the same or maybe even better than the i7 we recommended in games and such (it lacks hyper threading or wtv it's called but games don't use that).
I don't know about the video card, maybe the guys can comment: i'm playing on a nvidia 560m on my notebook and on a ati 6970 on my desktop. The 6970 is in some cases better than the nvidia 570 and the 570 is better than the 560.
While the 560 is certainly enough for now I don't know if it's not maybe worth investing in a 580 or 570.
Short story your config is solid

English defeated me in this post!