Thanks for all responses. I just knew that although this would be off topic, people would be interested in this.
Just to clarify: I've ordered a iBook G3 800 MHz, combo DVD/CD-RW drive, 640 MB of RAM, 30 GB harddisk, Airport card. The G3 had me worried, and I would have liked a G4 in the unit much better. I could have waited for the next revision that many hope includes a G4 in the iBook too. But a Mac owner I know that is not only interested in specs, but in real life experiences, told me the G3 is fast enough for my mobile computing needs, and I did miss having a notebook around, so I jumped in now.
The more advanced stuff will be done on my P4 1.7 GB, 512 MB RAM, 80 GB harddisk. A Sony Vaio, of course.
The ownership of the desktop PC made me less worried about installing programs etc. I will try to do it from the Mac too of course, but if I can't I can use my PC.
For those worried that I didn't look at other PC based notebook options: I did. I specifically did look at the entire Sony Vaio ( they rock! ) range, and the Tablet PCs. It's just that my hardware needs are limited right now, because I need the notebook less, and I really wanted to try out something new. That's the only way to learn exciting new stuff. Step off the known road, and go where you didn't go before.