THAT is exactly why you are having issues. Not because it isn't ready. Put Debian Linux as an alternate boot for your iBook. You'll have root and you can screw it up anyway you want. Ubunutu Linux has really taken a big leap here lately, get the PPC ISO burn it, resize your disk a bit and install it. It was just working on Friday of last week for me. Looks Awesome too... even comparable to OS-X.
Back your issue.
What Desktop Environment are you using? KDE, GNOME, WindowMaker, BlackBox, Crystal, Monster, Beast?
gtk == gimp tool kit
If gnome is installed... it should have a version. Might not be new enough, might not be compiled for the version you are running.
i686 statically linked is probably the best bet for someone that doesn't have thier own keys to the machine (i.e. sudo or root password)
Basically, rpm is what many distros use to manage application installations. apt/dpkg is what Debian based distros are using.
You see, you are used to a system where you can do what the hell you like. Well currently you have your own little domain in $HOME.
You can control many things, including financial gains from the place, but all you have to do is understand you don't have GAWD access. You are only a user(1), limited in the screwing up of your machine to your $HOME.
When you realize exactly why they are doing this, rather than railing against the whole thing, you'll understand why I force all of my Windows machines to behave a certain way as well.
It comes down to numbers, the more you let your users play, the larger and more heavily staffed your helplessdesk has to be. Locking down Windows is a joke, but can keep people from screwing up the machines. Locking down *NIX or Linux in your case is by default. If you nuke your machine... you only nuke your domain($HOME) not the whole machine.
And as for fixing the installation mechanism... tryout [link|http://fink.sourceforge.net/|Fink] for your OSX. You'll get an idea of what Scott was saying. That is the same installation mechanism that those of us using Debian Linux are using. (AS well as: Ubunutu, Xandros, Debian, Lycoris to name a few). I believe you will see why he says the installation problem is fixed, because it is. RPMers just don't know it yet.
Being this is the real first time you've *HAD* to use Linux... I can see why you are squirming being all userified vs adminified or rootified. I'd hate it myself.
(1) == or luser as many support people call'em