world space to screen space co-ordinates

Multiply the point by the world, view, and projection matrices. What API are you using?
You could use the D3DXVec3Project function in D3D, or Viewport.Project in XNA, or just multiply the point by the matrices yourself using the appropriate functions.

if you have your Camera's viewprojection matrix its simply

LocalSpace = viewproj * worldcoord (vertex by matrix multiply)

screenX = ((LocalSpace.x / LocalSpace.z) * (screenWidth *0.5f)) + (screenwidth * 0.5f)
screenY = -((LocalSpace.y / LocalSpace.z)* (screenHeight *0.5f)) + (screenHeight * 0.5f)

that'll get it to pixel position.

Ah, thank you very much both... I'll use both techniques to see which one I'll be most comfortable with... To answer Erik's question, I'm using C# to code it in... I browsed the forum prior to posting my question, but I saw solutions for C/C++...
Thanks again! :)

So another question...
I noticed XNA's Viewport.Project returns a vector 3... That's rather strange because screen co-ordinates have only 2 attributes, namely the X and Y co-ordinates. Needless to say Viewport.Project fails to accomplish what I'm looking for... I'm new to XNA, so perhaps I'm missing something... Does anyone know?

Thanks...
-TS...

It's a Vector3, but it's still in screen coordinates. X and Y will still make sense to you. The Z coordinate is the depth value in case you need it.