Have you guys never heard of GPartEd Live CD, a bootable ISO file with a graphical user interface for one of the most advanced partition utilities out there? You can resize and rearrange partitions as needed, in order to make more room for the root partition (you just have to figure out which one it is). It will test the resize and, if everything goes well, it will perform the resize including any data movement. No need to reinstall everything just because you set insufficient storage.
Obviously, as with any serious disk operations, you should have a full backup of any important data or settings before you run this, just to be on the safe side.
And next time you install a linux machine, make your life easier and use LVM...