The textures option is a lie.
The game doesn't recommend the "Ultra" textures setting for my 9800GTX but switching back and forth between "High" and "Ultra" revealed no performance impact whatsoever - not to mention that the differences in the actual graphics quality are very subtle - so I just left that option to "Ultra". Visually, the actual gameplay section of the game is similar to how things looked in Warhammer 40,000: Dawn of War II, only slightly more polished so if you could run that game well, SCII should not be a problem for you. Blizzard is not known to be a developer that pushes graphics technology to its limit and the same goes here for the most part. The real time cinematic however is a completely different story - these sections of the game definitely qualify as some of the best looking graphics I have seen across all gaming platforms.
The gameplay section looks nice but some of the special effects failed to impress.