Bit late but I agree with David...most of these minis use Atom processors so you can't do anything really intensive on them - games newer than the original pong are out lol - but they are great for surfing around, listening to music, bit of office stuff and watching stuff online that isn't high def. I've got one that is basically a little emulation machine - nintendo, c64, megadrive etc...
You can install operating systems using a USB stick - you don't necessarily need a USB C/DVD drive and I'm dual booting linux/xp on mine.
They aren't a replacement for a full 'proper' computer though!