Transforming lines..

I have a unitY length line (setup up so that the origin sits dead at the centre of it..) I want to render.. I'm trying to setup a method which will allow me to specify a start vector & end vector & the LineRenderer object will setup a transformation matrix to pass to the draw function to get my line oriented & scaled into the correct place.. I've tried a few different algorithms but the vector math is frying my brain so I was wondering if someone could help me..? Something like this: class LineRenderer { ... public void Draw(Vector3 start, Vector3 end, Matrix viewproj) { // setup transform matrix Matrix mat = ... ; // draw with transform matrix DrawLine( mat ); } ... }