Once you've loaded the simulator, the hard drive is not that big a deal anymore. It's done its job. The problem is in the session, while in the boat. The waves are pretty, the boats are pretty, but there is something wrong with the code of the software or the video drivers out right now.
I have an i7-930, 6GB memory, and an ATI 5870 1GB, running 64 bit win7 and I am not getting the smoothest of performance. If I put it to 4X AA or more its very choppy.
I think we may be some patches, or drivers away before this gets smoothed out for some of us.