Like crosbyharrison, I have just one account. I see no need for an admin account, since you need to enter your admin password to run any installer or software update in any event. Note that you don't need to 'install' (in the PC sense) all software - most off-the-internet applications come as .dmg files (disk images), from which you just drag the app to your Applications folder. I'll add a second account once my daughter gets old enough to use the computer, so I can enable parental controls there.
Do choose your 'shortname' carefully when setting up your account. It's not something you'll use, per se, but you'll see it as the name on your Home folder.
Personally, I did customize the install to save a bit of HDD space (omitting non-relevant printers saves several GB, and since I personally will never use GarageBand, omitting that saved several more).
Agree that Terminal is not your friend, unless you're familiar with using a command line interface in Unix (which is the basis of Mac OS X). As a casual user, you should never have a need to tinker in the Terminal. One simple example from the 'don't try this at home' file - the Terminal command "sudo rm -rf /" will erase your HDD. Not very friendly at all. []
Apple Mail is excellent (in OS 10.6, it can directly access MS Exchange accounts).
Spotlight will use compute cycles initially, especially if you migrate files from a PC. After the first few hours of indexing, it's quite innocuous, and useful for finding files.
Adium is only 'better' than iChat if you need to use chat servers which iChat doesn't support. iChat supports AIM, MobileMe, Jabber, and GoogleTalk. If you need to IM with someone using MSN or Yahoo, Adium is a great choice (supports just about every IM platform out there), but no AV support.
I'd stay away from FileVault - encrypting your entire user folder as one large sparse disk image is not the best idea Apple came up with (a power failure during an HDD write can damage the file being written, and if that file is really your entire user folder...). Instead, for your financial information, etc., simply use Disk Utility to create a secure (encrypted) disk image. UNcheck the box to store the password in the Keychain when you create it (and don't forget the password!!). I keep my taxes, lists of CC numbers, etc., on an AES-256 encrypted image, which is 'theoretically' unbreakable.
Really, on the hardware side, the whole thing is basically plug-and-play.
On the software/shareware side, look at:
- Flip4Mac and Perian - allow other media types to play natively in your web browser (.avi, etc.)
- MPEG Streamclip - an excellent (and free) video format converter (but Canon cameras already shoot video in the Mac-native Quicktime format)
- SuperDuper (or the free Carbon Copy Cloner) - makes bootable backup clones (or, just use Time Machine!)
Also, I use a couple of menu bar add-ons:
- WeatherDock - weather.com conditions/forecast in your menu bar
- iStat Menus - RAM usage and CPU activity in your menu bar
Mark, you also asked about iWork. I have it, and I have MS Office for Mac. Pages and Numbers are just 'ok' - they do fine for standard word processing and'light'spreadsheets. Definitely a Mac OS user interface. Numbers' charting capabilities are a bit weak (but very pretty!). In terms of interoperability with MS Office, while it's true that you can open and re-save or export as MS Office files, there are frequently unexpected formatting changes, etc. It's not a perfect setup, ok for casual use (sending letters back and forth with a Word user for editing), but not optimal for laying out something like a newsletter in a cross-platform setting. Keynote, though, is a thing of beauty. Still not functionally mixable with PowerPoint for working on the same file, though. However, when I give seminars/presentations that I made in Keynote, the audience is always impressed - the slide transitions and builds are eye-popping but in a tasteful way. But, when I'm working on typical documents for work (where Windows is the norm), I use MS Office on my Mac to edit/create those files. So, on the whole, iWork is ok, but IMO if you're used to MS Office and use it frequently, get MS Office for Mac.
One final recommendation - if you have questions as you go through the switching process and beyond, a great place to go for answers is the Apple Discussions forum. There are subsections for the iMac, general Mac OS X questions, and many Apple applications.
Have fun!!
--John