"Jittery" texture on terrain

I need to lay out high-resolution textures on a terrain for an educational project I am working. When I put the texture on a cube it looked pretty good. Then I put it on a terrain and it looks really bad, all jittery and badly compressed. How can I get around this. Does Blitz support DDS formats?

Gazzaden

Jittery? I can't figure what you mean. You can scale the texture if that's the problem.