opengl, c/c++, texture projection to uv space

I have a model (that I can render to the screen using gldraw) with uv coordinates (wasn't able to get texture displayed, haven't tried hard yet). I have a texture file for those coordinates loaded into an opengl texture. What I need to do is project the texture to a window using their UV coordinates instead of their model coordinates using an orthographic projection. In THEORY I know how to do it, in reality it doesn't do what I expect it to do :-)
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