Buying it now does seem very tempting to me simply because of the idea of having a better system.
However, I decided to wait.
I thought about this quite hard, and I don't think waiting for 1 month can't do any harm to me.
Here are some reasons that makes me think I shouldn't upgrade yet.
1.) I don't play anything just yet except for Starcraft and CSS, which aren't graphically demanding at all.
2.) I only really want to be able to playDiablo 3, Starcraft 2 and FEAR 2 on max or near max settings, which are not even out yet, so there is no point. I'll probably play other games too, but those 3 are top priority to play

3.) There is no harm in waiting, I can't imagine the price of HD 4850 going up. As for the new one's that are coming out, there is no way I can tell what their price would be on release, but sure enough, the HD 4850's price won't move, it can only go down.
4.) 3 weeks to see whats up really isn't much of a wait.
Thanks for your opinion's guys.