|SR does store other data, such as hibernation data (not the raw data, but apparently meta data), and other progs do write to it occasionally. You can explore the partition via a Linux boot disk (I rec Puppy) and delete what isn't necessary. But be careful, because what is necessary really IS necessary, or you'll break your boot. I would do an image of the partition and also burn a Windows repair disk.|
Or you can expand the partition to make more room, or possibly turn off hibernation. Or just use a third party backup prog to make the image.