How can I purchase and install additional memory in my powerbook G4?

Question

I've got to install more memory into my powerbook G4 (currently just 256 MB  of DDR SDRAM, only 3.2 GB of free disk space and 1.5 Ghz PowerPC G4 processor).  Can someone point me toward a supplier of the memory cards I need, as well as a tutorial for how to do a self install?  I don't want to sink $$$ at the mac store on such an aging machine, but I want to keep her running as long as possible.  How high can I go with the memory on this machine given its restraints? 
While I'm at it, is there anyway to amplify or boost the wireless signal receiver?  My machine has almost zero bars of internet connectivity in places where other machines have 4 bars. 
Thanks!  =O)

Answer 1

Did you physcally look at the RAM slots to confirrn two modules are installed? Do that before proceeding. It's very important--for some reason yours may have been ordered with only 256MB. Opening the RAM slot cover is a user-doable/approved operation
There was a repair extension program for the 15-inchers' RAM slot problem, but it's now long-expired. The next step is only if you physically can see two modules: If you feel that, as the original owner, this was not properly communicated to you, you could make a cool-headed and document-backed plea to Apple Customer Relations (1-800-767-2775 in North America).
"Is a logic board the same thing as a motherboard.. "
For all practical purposes, yes. Macs have logic boards; PC's have motherboards in common terminology. They are the mounting point and connectivity path for the processor and most other internal components. Presumably, the "mother" part was derived from epithets flamed forth by disgruntled PC users.
BeebleBrox has already linked one RAM vendor I use, Other World Computing. The other is Data Memory Systems:
Apple PowerBook G4 1.5GHz 15" Screen (200 Pin PC2700 DDR SODIMMs)
I've ordered all my Mac RAM from only these two vendors for close to a decade and am very happy with both.
256MB RAM with OS 10.4.11 is like saying someone has an IQ of 10 but it takes 12 to grunt. My older PBG4 at 1Ghz also has 10.4.11 but 1G RAM. It does fine. A lack of RAM makes the Virtual Memory system spend a lot of time writing data to the hard drive when there is no more RAM available. The slowness this VM operation induces gets worse as the free space on the HD grows smaller as you add files and programs.
I don't think low RAM or a bad RAM slot would cause the wireless connection issues. The antenna is in the display frame as I recall. There are a lot of reports of a negative change in ability to pick up wireless networks being traced to other wireless devices in the area. See what's been added to the house/office that is also wireless.
What I don't know is where you are. I answered with the potentially flawed assumption that you are in North America. OWC ships internationally, but I don't believe DMS ships outside N. America without making you jump through hoops and hedgerows. Post your geographic locations in your profile info and it will make it easier for people to respond to the common "where can I get" questions.
This grew long, but what you need to do before anything else is open the RAM cover and count modules (They are "stacked" so one is covered by the other but should be visible). As I now know your screen size, I can link the instructions for doing so:
RAM