Burn image to SD card

You can do it from the command line as well. No need to install anything.

1. Find the name of the device of the plugged in SD-card. For instance I typed ls -la /dev/sd* before and after plugging in the sd-card. I saw the date of /dev/sdc change and thus decided that that was the one.
2. Find the place of the unzipped image, which was /home/username/Downloads/2012-10-28-wheezy-raspbian.img for me.

Type the following (mutatis mutandis):

sudo dd if=/home/username/Downloads/2012-10-28-wheezy-raspbian.img of=/dev/sdc 

or with improvements suggested by other users:

sudo dd if=/home/username/Downloads/2012-10-28-wheezy-raspbian.img of=/dev/sdc status=progress bs=4M 

and wait for the command to return. It may be quite a while, especially over usb2.

Resizing can be done from the Pi itself in the raspi-config program that starts automatically the first time you boot.

Be careful. Make absolutely sure the device name is that of the SD-card. If you replace it with the device name of your hard drive, your hard drive will be overwritten.