Extension the size as given in one of the previous reviews didn't work for me. However the instruction give at www.raspberrypi.org/forums/viewtopic.php?f=2&t=4382 worked for me. You can open an second image in QEMU where you can resize /dev/sda1 using program gparted. So 1) copy the image to raspbian.img 2) resize by qemu-img resize raspbian.img +2G 3) Run both images as: qemu-system-arm.exe -M versatilepb -cpu arm1176 -hda 2012-07-15-wheezy-raspbian.img -kernel kernel-qemu -m 256 -append "root=/dev/sda2" -net none -drive file=raspbian.img 4) sudo apt-get install gparted 5) Startx and run sudo gparted in the command window en select the second partion and resize it. 5) You new larger image is then raspbian.img.