In case you're taking about AlBook (only one not replied to yet), you lay it upside-down on a table, remove the battery (3 seconds), unscrew 4 small screws (less than a minute) insert the RAM, press it down (30 seconds), put the lid back on and screw the screws (1 and a half minute, maybe), re-insert the battery (3 seconds)
Now flip it over, and start up.
Didn't take you 5 minutes, and you didn't void any warranty. The instructions are illustrated and come with the PowerBook when you buy it.