Terrain modeling

How can I import a 2048 X 2048 heightmap into blender so I can poly reduce?, or even better apply a heightmap to a subdivd plane?.

make sure it has a material then go to the texture buttons, then select new then image, then just load it from wherever you saved it

The thing is whenever I use the noise tool it seems to tile my heightmap. Is there a plugin that will load heightmap data?, or should I just export a smaller mesh from my terrain editor and REALLY scale it up inside blender so I can export to my engine?.