I have read here about some of the flickering and twitching in the game and I have experienced them first hand within hours of starting to play the game. 

In my case the images started to tear and flicker typically in the lower half of the screen and in particular in the sub-screens like the Blackmarket or Tech Trees. It doesn't like the overlaying of an image for some reason. Today I turned off "Crossfire" in the ATi Catalyst Control Center and voila no further issues!!

I play other games in Crossfire and have never seen a problem.  And oh yes, I keep up with the latest drivers!

If your having trouble with either ATi or Nvidia cards and you are running more than one you might want to try shutting the other cards down.

2 x X1950 Pro in Crossfire (no overclocking)
MSI K9A2 Platinum
AMD Athlon 64 X2 Duel Core 5000+ overclocked to 3.10Ghz
2 GB of Kingston RAM
WinXP Professional 32 bit