My laptop, handles CMBN quite handily for the most part. I have a little bit of a stutter when scrolling too fast, but it is acceptable for the beautiful rendering of the terrain. It does the replays without a hitch.
My rig:
Asus G73JH-A3 Republic of Gamers 17-Inch Gaming Laptop - Black
* Intel i7-720QM (1.60GHz Quad-Core)
* 8GB DDR3 1066MHz, 4 SODIMM Sockets, up to 8GB
* 1TB (500G 7200RPM x2) HDD; Blue-Ray Disk Combo Drive; 802.11 b/g/n
* ATI 5870 Graphics with 1G GDDR5; Windows Home Premium 64-bit Operating System
* 17.3-Inch Full HD (1920x1080) LED Display; 2.0M Webcam; Gaming Backpack and Mouse
I will be rebuilding my desktop soon, as it is a couple of years older than my laptop, and I can see it needs upgrading to get the most out of CMBN.