hi friends I'm going to make a small game comprising a huge terrain, and perhaps with a plane flying around the landscape (anyway), what's the best way to make this huge terrain? I mean both from a modeling view and a programming perspective? can I split my mesh? octrees? or you recommend something else? speed has the top most priority because of the great size of the map (which would later include textures, sky, lens flare and many more effects) please help me where can I find more info and some sample (with code also).... thanks www.galaxyroad.com

The usual first thing to do is to get a quadtree rendered terrain going. After that, you can look at various level of detail techniques.

Check the Graphics Programming and Theory forum FAQ, the "Special Effects" section, under the "Terrain" subsection. There's a couple of good links to places covering LOD techniques.

I personally recommend Chunked-LOD (see link above).