I'm a PC person. My wife's a Mac person (back from the Apple II LC days). But she just uses it and doesn't bother to worry about the technical aspects.

We bought a dual processor G5 ~ 6-9 months ago. It's a nice machine. She also has a 667 MHz 15" Ti Powerbook.

I tried adding Fink Commander to the TiBook and installing some software to play with. I was able to muddle through it with almost no understanding of *BSD or OS X. Of course, I gave up after a while because I really didn't have the time to understand the details and she didn't need the stuff anyway. If you're interested in adding OSS to your OS X, Fink Commander is probably the way to go (check out danreck's and tjsinclair's comments with Site Search). (Though recall that Todd Blanchard had trouble with Fink.)

I bought a couple of OReilly books on OS X (the Panther Pocket Guide and the Missing Manual (I think)) but have only skimmed them. I was looking for books that explained, or at least mentioned, installing OSS using Fink Commander at the time.

I've set up accounts for both of us on the G5 but haven't really done anything complicated with them. The things I need to understand better are: 1) What's really happening when I install new software? What's going on with these Disk Images and the Drag-And-Drop Installation? Where should new software be put? 2) How do I adjust the file permissions so that she and I can each modify files or use programs without dragging them to a shared folder?

Otherwise, we really don't need to think much about what's going on. It really is a turn-it-on-and-use-it type of machine for the most part. We've installed MS Office, Mozilla, and Eudora on the Powerbook and done an update to Panther, and got wireless networking working with it. On the G5 we've installed MS Office and use 100BT Ethernet. The Mail application with Panther is pretty good - it's got a pretty good spam filter and transferring Eudora's mailboxes was pretty painless as I recall. Both of the machines are easy to keep updated using Software Update. We use a Canon i550 printer with the G5. I haven't figured out how to print over the network using the Ti PowerBook yet, but haven't spent much time on it.

Some things are different than on a PC - e.g. sometimes the Backspace and Delete keys don't work the way I expect. But for the most part, using a Mac isn't too different from using a PC. Some things on OS X are very Unix-y (especially the file permissions stuff), but if you're the only user it shouldn't be much of an issue.

If you're looking for a manual, I'd browse OReilly's offerings. They're probably the best these days. Most of your questions can be answered here or on the web with time, but I understand the joy that comes from holding a good book.

I hope this bit of rambling helps a bit. Best of luck!

Cheers,
Scott.