Okay....

The hardware texturing channel is a little buggy, it always has been. Having a good graphic card will help, and also quality textures, but the highest setting such as the 256 setting may actually produce a far worse display than the lower settings. So I would try to determine the best output for your texture, you may find a lower setting better.

What resolution is the texture?

Also, viewport 2.0 is not really that great unless your system can handle it. Just because Autodesk demo it working really well for them doesnt mean it will work for the rest of us.

J