Thanks Mark.
I'm going to try with the minimum I listed for a start, and can always upgrade one end from the 642.
I wonder if there's a discussion here about the relative merits of outdoor directionals i.e. Yagi vs. flat panel vs. Backfire . . .

On satellite end, I'll have a simple Dlink switch (or similar) from sat modem to PC and antenna, other end is the 642 in a window feeding PCs in that house.
Wish me luck!!