Hey Johnny,
good questions/points...
Apple (as well as Intel, Dell, M$FT, Lexus, GM, etc...) has always wrung a lot of profit out of the people that convince themselves (rightly or wrongly) that they need the absolute fastest, most powerful, biggest, most expandable, most whatever.
At the other end (eMac), they are selling on razor-thin margins to keep market share with those people that might switch suppliers based solely on price.
In the middle is the fertile ground for the reasonable mind/wallet. I wasn't aware of, nor can I explain the reason for, the large markup in your region, but I would only recommend an iBook for someone who only does email, web surfing, general office stuff, rips a few CDs to iTunes, and maybe fires up a game or two on rare occasions, but for whatever reason absolutely *needs* portability. And in such a case, I would wholeheartedly recommend an iBook without reservation.
As soon as you break out into any graphics work, page layout, more serious gaming, video editing, major (like 30+GB) mp3 library, I have to go with the bigger screen and better video chip of the PowerBook. Again, though, portability must be essential for the user.
For most people the premium paid for the convenience of occasional portability isn't worth the sacrifice in power. My own mother is on the verge of replacing her original (1998 bondi rev A) iMac. She is drawn to the PowerBooks, but I am strongly steering her toward an iMac *5 because all she wants out of her portability is occasionally using the computer by the TV downstairs. 20 lbs of iMac moved once every few weeks isn't that much different than 7 lbs of PowerBook. But the iMac's vastly superior measure in every specification and benchmark (besides weight and size) at the same price point far outweigh the size/weight issue *for *her *needs.
Since you never mentioned a desktop system, I've been assuming that portability is a must.
Now my personal approach is to buy one notch down from the fastest/spendiest in whatever line (desktop, laptop, monitor, car, TV, etc...) I'm purchasing. In the case of Apple notebooks that would be the 15" PowerBook. At my office, we have 3-year-old Titanium 15"-ers still in service with plenty of life left in them. I wouldn't put them up against a dual-Athlon in a Doom 3 death-match, but that's not what they're used for. (If it were, I wouldn't have bought notebooks at all.) At home I have the original *3 PowerBook coming up on 7 years of service. That was my one dabbling with the top of the top-end. If that old machine can last for 7 without major issues, I would have no doubt about the current 15" PB doing just fine for the next 5. Whether or not speed will be OK depends on what kind of work you're doing 5 years from now. If you start working on your independent feature-length CGI cinematic masterpiece using Maya and Final Cut before then, you'll probably want to upgrade. If not, you'll be OK.
About your pixel question - a pixel is one RGB dot on the screen. All monitor resolution is measure in horizontal and vertical pixels. In Windows, the various resolutions are referred to as VGA, XGA, UXGA, etc... In the Mac universe, we just use the numbers (640x480 = VGA, and so on). The iBooks (12 and 14) are both 1024x768. In the 14" iBook, each dot is a little bigger, but they both display the exact same amount of information. Although the video chip in the iBooks can supposedly extend the desktop to another screen (called monitor spanning (vs. mirroring where both screens show the same image)) Apple has allegedly disabled this feature - probably to justify the premium price of the PowerBook or to preserve performance which *can* degrade if you're displaying more pixels at a time. The current 15" PowerBook monitor is 1280x854 - I don't know what that is in Windows acronyms, but the end result is that you can see about 40% more web page, Sim city, page layout, photoshop image, or whatever it is that you're doing.
