I'd suggest just installing Ubuntu 8.04.1 is the current version IIRC, download the ISO image of the installer CD, install it, and use it for your POP email (thunderbird / evolution), WWW (firefox), Office Applications (OpenOffice's various programs Writer/Impress/Calc/et. al.), image viewing / photography (F-spot, Digikam, GIMP, et. al.), reading PDF files (evince, document viewer, xpdf), et. al.
Learn how to shut down the system via the graphical menu option / icon.
Learn what the mouse buttons do (pretty much what you'd expect with a few nice additions)
Learn to use the package manager to search for / install new programs.
Learn to accept the update manager's request to allow the system to be updated by new s/w.
Learn to use tracker based search tools to index your files and search their content / titles
(actually this bit seems a little harder than I'd expect on my Ubuntu box; I haven't quite figured out what I didn't configure that it wasn't basically "automatic", then again I usually use Fedora)
Get familiar with using the multiple virtual desktops, window management (expand/contract/minimize/always on top et. al.)
Get familiar with the file explorer to navigate around your files / directories.
Learn about a few new utilities/programs to suit your interests, install, use.
Really after that you're in pretty good shape for day to day operations. You can certainly even discard about 80% of that and still be more proficient in a computer literacy / "get the job done" sense than most people are with Windows / Macintosh.
Unless you have a bad crash or mess something up you usually don't HAVE to learn the command line stuff, boot parameters / boot menus, file system repair, disk administration, et. al.
Knowing how to do some backups would be good once you start to keep important stuff on the system. In the simplest way just get an external USB/eSATA hard disk or flash disk and just drag/drop stuff to be backed up into a new folder you create there. More advanced techniques are automated full / incremental backups, use of partition imaging / compression s/w, backups to a different PC or over the network etc.
Burning a CD/DVD from an ISO image is pretty much just a couple of clicks in the file explorer, and burning random files to a disk is about the same. Easier than Windows since the S/W for it is installed by default, not a 3rd party package.
Learn to monitor your free disk space; I'm sure there are basic GUI tools, or "df -h" at the shell prompt works.
Printing can be a headache depending on your printer's compatibility.
Networking should "just work" if you connect to an ethernet based modem/router, and your ethernet card is supported. Otherwise, well, it gets messy.
Wireless networking will either pretty much "just work" if your modem is supported, or, well, it gets complicated.
Sound should "just work" if your hardware is well supported, or, well, it gets complicated.
Ditto for scanners, digital cameras, MP3 player synchronization, PDA synchronization.
Media playing (MP3, DVD, MKV, AVI, WMV et. al.) from files is usually a little broken by default. Learn to install "mplayer" in a full build (not one of the stripped down ones). VLC from videolan is good too. Others like gstreamer, rhythmbox, xine, xmms, whatever have their uses.
If you want to learn shell usage, find a good BASH tutorial and get familiar with the built in documentation pages on almost every command e.g.
man date
for the manual on the date command
man bash
for the BASH shell manual et. al.
learn ls, cat, grep, man, less, find, xargs, diff, sed, whatever.