No, at least you shouldn't... But it couldn't hurt to write the pertinent info down before upgrading. If all goes as planned, you don't need it, but if you encounter any hiccups along the way, you'll be glad you have it.
I plan to upgrade from 10.4.11 to 10.5 on my PM G5. Will I have to reset any of my wireless net work settings after upgrading to 10.5.
Currently running wireless with an Airport Express and a wireless printer.