Thanks for the reply Ian, and I guess that if I actually had a Pi in my hands and was able to experiment with it, I would learn things a lot quicker, but it is lines like 'Then rsync the raspbian rootfs from p3 on the SD card to sda2 on the Samsung disk.' and 'Hand edit fstab to add a swap entry for /dev/sda1 then "swapon -e -a....' which make me think "what on earth is he talking about!"
Ah, ok... well for the sake of completeness then, I'll try and expand on that bit:
"rsync" is a kind of "copy", but a bit smarter and really meant for copying stuff from one machine to another, but you can also use it to efficiently "clone" filesystems and directory hierarchy's on the same machine, so I am using it here to make a clone of the rootfs partition on my SD card, into a partition on the USB disk.
So, what I did was, mont both the SD card and the USB drive on my (ubuntu) laptop and then:
rsync -avxS /media/mmcblk0p3/ /media/sda2/
Where /media/mmcblk0p3 was where the laptop saw the rootfs partition of my SD card and /media/sda2/ was where it saw the partition I wanted to write to on the USB drive.
The options to rsync are pretty complex (and frequently pretty opaque!), but you say you have a linux netbook, so spend some time at the shell prompt, and try "man rsync" to figure out what the options are doing - it's god exercise!
Prior to that, I had used the gparted tool to repartition the USB drive into two chunks, small one (a few gigs) in sda1 for a linux swap partition, and the rest of the disk formatted as ext4 for the new rootfs.
Note that, with such a limited memory as the RPi, you are going to want some swap space or many programs just will not run...
Anyway, once the system booted, it did not find the big chunk of swap I'd allocated. And issuing a "swapon" command did not work - other than complaining that it could not find /dev/mmcblk0p2 (which is where the swap was on the stock raspbian SD card.)
Now, historical unix system used a file called "fstab" (file systems table) to record where the file systems were, but a lot of modern linux/unix system do not actually use that file much, though it still exists.
However, swapon does still look in fstab to see if there are any swap file systems listed that it can try to load, so editing fstab to add an entry for /dev/sda1 (which is where my "new" swap partition appears) and then issuing a:
swapon -a -e
Did the trick. Again, try "man swapon" for details, but in brief the "-a" means "load all the swap partitions you can find" and the "-e" means "ignore any errors for partitions that do not actually exist"...
Having said that though, I am sure that once I start to learn a bit more about using the Linux command line (and have a Pi to play with) things will start to fall into place a bit more.
You say you have a linux netbook? If so then just playing around with the shell in that will help, since the shell looks "the same" on all *nix systems, more or less. There's nothing particularly unique about the R-Pi in that regard.
My current thoughts are to set up something like QEMU (maybe on my Linux netbook) in the meantime to familiarise myself a bit more with what to expect.... and to realise that I must learn to walk, before I try to run! ;)
As I said, just using the netbook should be enough - emulating the Pi is probably only useful if you want to try cross-compiling code for it or something. If all you want is to get to grips with the linux "experience" initially, then any linux system, whether x86, arm or PPC or whatever, will work in pretty much the same way, and the commands and applications are basically the same.