Im after some pre-upgrade advice really, as we dont run 6.5 yet...

We have 5 Netware 6 servers on our NDS/Edir tree, which spreads over 3 UK
sites (connected via VPNs).
3 servers live at head office, and the MASTER replica is our main server.

We are buying a new server very soon, to replace the main server at head

Im after some advice and guidelines/pre-requisites for upgrading our MASTER
server to 6.5. How will this effect the rest of the tree? Im sure there's a
usefull guideline document out there, but any "real-life" tips or precedures
would be most appreicated.