I have a question for you concerning hardwood installation. We have a large
space that makes up several rooms. We are thinking about laying one section out
in a diagonal (I know it makes things difficult). But my question is this:
Between the 'straight' laid area and the diagonal I was going to install a
perpendicular board as a transition. Do I need that or can you butt up the edge
of the diagonal board to the straight one? In either case do I need to slot the
end of the cut diagonal board to accept the groove (of either the transition
board or the straight boards)? If so, what is the best way to do that? I do not own a router but will bite the bullet is I have to!!

Thanks,
Mark

do you think a T interface would help? like this

The diagonal field should be grooved to receive the straight run boards. Most guys will use a router with a top bearing slot cutting bit.