Yea, my iBook G3 (specs in sig) was my first Mac and I've had it for about 6 months now. I got my iBook from a trusted store online as a used/refurb. It came from them with the power brick, Airport card installed, and 256mb RAM. I now have it at 640mb RAM. Otherwise what you see in my sig is what I got for around $490. Granted, I would say that was stupid of me to pay when I look at it now, but o well. I just wanted something from a trusted store and not some Joe Schmo, plus the airport card was a huge plus and necessity for me. I also wanted the 40gb hard drive. Did I pay a bit too much? Yes. but I'm extremely happy with my purchase.
For your purposes I see no reason why a 500mhz or 600mhz G3 wouldn't meet your needs. I got the 900mhz because it is actually my main computer. Safari, Mail, iTunes, iCal, Photos, iPod and it handles it awesome. For you I'd say if you want an iBook that will run OS X smoothly for what you want...a 500mhz-600mhz should be fine. You could most likely find those for around $200-300. I see no reason for a G4 iBook based on your needs. The iBook G3 is still extremely capable of handling everyday tasks plus a little more with the wonders of running OS X. 😀