Why is my G3 iBook draining the battery so quickly?

I've a thread going on this at the Apple discussion site. My G3 iBook is sucking down my new battery. Recent changes include:

1. a new hard drive (15GB -> 40GB) with expert disassembly.
2. changed LAN encryption from WEP (pathetic) to WPA 1.
3. restored OS image using Carbon Copy Cloner.

Things I've tried include:

1. Reset PMU.
2. Zap PRAM.
3. Repair permissions (no problems, this never seems to work)
4. Deleted the .plist for power management.

Here's part of the recent thread. Comments welcome!

Apple - Discussions - Power drain after drive upgrade?

I did some research and the drive power demand increases typically measure out at about 2%. Sometimes newer faster drives consume less power than older slower drives!

I could imagine that Panther might have some trouble with optimizing sleep on some of the newer complex drives (which are really full-fledged computers with databases, operating systems, algorithms,etc) -- if I can't figure out anything else I'm going to upgrade the iBook to Tiger. (I hear it works pretty well if you disable Spotlight and maybe the widgets.)

More interestingly now I'm focusing on WPA wireless encryption. I changed my LAN's encrytpion from (so broken) WEP to WPA around the time of the drive switch. I notice the G3 iBook doesn't support WPA 2 (10.3.9, latest version AirPort) -- makes me wonder if there's a CPU math constraint that the G3 can't meet. That in turn makes me wonder how well the vector-less G3 actually does with WPA. If the CPU is churning that would increase heat, turn on fans, etc.

I'm going to install some tool for CPU resource utilization and study what's happening with WPA, the compare to WEP.

Update: this is a very interesting evaluation of encryption and performance, but not particularly looking at power consumption.

Update: Using OS X's monitor tool and the freeware (forget name) dashboard app I can see my iBook CPU is working quite hard to do web page access. I'm suspicious that WPA is a bit much for a 600MHz G3. Too bad -- since it works very well with XP SP2.