I found Pogue's "Missing Manual" for OS X useful and comprehensive. I'd been using the previous iterations of the Mac OS from 1984 forward at home and from 1987 forward at work, and had attained a certain fluency: I could diagnose and fix almost anything that went wrong in that comely yet—alas!—increasingly unstable environment, and reflexes born of long habit (the reason I gave up years ago attempting to convert the casual longtime Windows user: the protocols, however superior, would seem counterintuitive) made working in that environment all but effortless. The switch to OS X was something of a shock, and I'm still something of a tyro in the diagnose-and-fix department, but fortunately things don't go wrong anything like as frequently. The "Missing Manual" was a big help as I made the transition.
As to hardware, for your needs the iBook G4 will do handily. Do get additional memory (768MB should be comfortable); don't pay Apple's RAM prices. It's always a good idea to purchase in the wake of the MacWorld Expo, as last year's hot boxes are frequently available at steep discounts.
I've just concluded a deal with an [link|http://www.powermax.com|outfit in Oregon] that appears to have some fabulous deals, and will report early in the new year as to whether the experience justified my optimism. I will note that Oregon apparently lacks a sales tax. I will further note that under California law we who purchase big-ticket items from Oregon must pay a "use tax" (equal, oddly, to our state sales tax) on these auslander acquisitions. I will observe finally that of course we all report and duly tender tax on these transactions, and add, with Dorothy Parker, that I am Queen of Romania.
cordially,