I have Menumeters running so I can always see how much memory is available, even an if-then interrupts without you realizing and probably will get annoyed quite fast, if you do it manually you can do it when you do something else for a moment(make coffee-toilet visit-etc.) so won't interrupt.
Usually when I do the purge command through terminal, it takes no more than about 20 seconds. Am I doing something wrong?
No, not that I am aware of, there is a site which tells you how to map the memory in the lower slot in open firmware(did that), the powerbook sees the memory(2GB) but crashes as soon as it needs the second memory chip, probably due to the fact that the speed is not set on the lower slot.
Some people had luck with it, but after each restart you had to go into open firmware again and type quite a bit to get it to work again.
The memory slot is not broken, Apple refuses(d) to update for obvious reasons.
That seems like too much of a hassle unless there's an apple script that can do the same thing for you that starts at login; then that might not be so bad.
The more RAM, the better, OSX can be a "sucker" for memory.