If all you want to do is get some media viewable on XBMC, then just throw some stuff on a FAT (or FAT32) formatted USB memory stick. XBMC will be able to see and play them all.
If only I'd had the common sense to think of this before....
So far today I've been through setting up an Ubuntu Vbox and failing to get it to recognise my SD card. I then moved onto an Ububtu live CD in my laptop first to resize the ext4 partition and then to copy a bit of sample media onto it to test. About 3 hours in I finally got to test it.
End result though, it played a 1080p mkv smooth as silk. Well chuffed.
I am being drawn towards Raspbmc instead though, for the simpler Windows setup and the auto updating.
Also, I've robbed my SD card from my camera to test. I will need to buy one for the Pi just for the OS. What is the recomendation? A decent branded 4GB Class 10?