I'm getting the same thing, and I have the 8400GT. But sometimes it's fine? Maybe it is lag? Generally for me it happens when i'm on the ground, but certain systems (Such as Reglus) seem to have the effect as well.
The game tells me I need to update drivers, but every time I download the Nvidia update it tells me my card is not recognised!!
I was having the stutter issue.
I run a nVidia card.
There is a new driver. it was released after the date stamp on your post.
Also, go update your sound drivers.
For me the issue of ground / starbase stutter was fixed with 2 new drivers
Op try switching off the AA or dynamic lighting.Also try changing your proxy,if it is at either EU/US then change to none,if it is none try the proxy from where you are,also they are working on the proxy's so maybe when you try next it could be better
Nabs420 the 8500 is not a gaming card,set everything to low including res and build from the ground up,it may have worked but the reason that Cryptic name min specs is they know that is what is required to run the game.
It is ok to say "it worked in beta" etc but the devs know they will be adding to it and your card is well below the min specs.