You might have a problem with the card reader, I have had limited success in simply reading those things, from working perfectly (ASUS laptop), to complete system freeze on insertion (HP laptop).
That's why I bought an SD card to USB adapter, as USB is much more universal and simpler standard.
Plus if you get the microSD cards, you can also use a micro to normal SD adapter for use in cameras/computer, so you get the best of both worlds. Then you can also use them in your mobile phone as well :).
I was looking at a 16gig microSD card in Officeworks last week, although the price was higher than 2x8gig cards, it was still quite tempting.
Webcam drivers are kernel based, the reason your camera is now working with the latest version of Ubuntu is that it has a slightly more uptodate kernel. This is also true about card readers and other devices. Generally the better device support comes with later kernels. One reason I never seriously adopted PC LinuxOS. it uses an older kernel and has no support for my wireless card.
Of course you could simply (simply?) download, compile, and install the vanilla kernel from kernel.org, but then you would lose some distro-specific features.
But it certainly is fun playing around ;).
As for your question:
*Oh could I ask another dumb newbie question: with virtual box or using a thumb drive, can I do a ground-up install of Arch (or slackware or whatever I'm playing with) just as though I was installing it on an empty hard drive then?*
Yes, you can. Just be careful where the distro puts the GRUB bootloader. You will want it on the USB stick, NOT on your hard drive. That can be a bit hard to figure out with some distro's installers, so be careful. It won't (read as: SHOULDN'T!!!) mess with your current hard drive installation, but if it doesn't detect all your current OSs in menu.lst, then you will have to rebuild them.
As a complete safeguard against that behaviour, and to make things simpler, I simply remove my hard drive when installing onto a USB stick. Then there is no doubt.
And it is NOT a dumb question, the only dumb question is the one you didn't ask because you thought it was too dumb to ask :D.