Ok, I thought this was just Metaseq acting up with my graphics card but Blender does this too. 

When I go to attempt to box model a head I do it in the fashion of drawing in edges that I need, keeping subdivisions down to a minimal.

In Mod Tools I can do it quite fluently but Mod Tools has its own, specific edge creation pencil which is different from its knife tool.

Metaseq and Blender feature the knife tool only.

The problem that I'm having in both programs, even with occlusion turned on, is when I go to create and edge, say on the front of a cube, the vertice on the top edge and vertice on the bottom edge will sprout two more edges creating a triangulated face on the top and bottom of the cube.

Is there some function that needs to be turned on besides occlusion that will force either program not to create extra triangular faces to connect to the edges that I"m attempting to create?

Also, if this is a bug and it's worked out in Blender 2.5 - would you suggest just going for 2.5 even though it is still unstable?