Wheel building query - Where do I measure various things from?

could build the front x4 and rear x3 (actually am i being too crafty)

I could. I'm still considering exactly how to go about the build. I've never done a 40h rim before. I'm probably just going to do a direct copy of what's already there. It's a tandem, see.

http://www.wheelpro.co.uk/spokecalc/calc-measure.pdf

Nice info there, should sort you out.

Thank you. That's exactly what I was looking for. I knew something like that existed, I just couldn't find it...

I knew this forum wasn't just mudflinging, crap jokes and beer... :)