I sat the CK exam on July 2007, after 3-4 months revision. I was really happy to score 99/263.
About 70-80% of the exam is Internal Medicine, and the rest is divided between surgery, paeds, obstetrics/gynaecology, psychiatry and ethics.
Again Usmleworld is a great resource. Use it for improving knowledge, and jot down notes. Kaplan Q book is also very good, but sadly I found the online Q bank fairly useless. Crush step 2 is another good resource with high yield facts.
Finally, clinical experience helps pass the test, so if you can be active clinically that will also help.
Certainly I quite enjoyed studying for this exam. I am currently doing General Practice, so I was always using the information that I was learning. From that point of view GP is quite good as you see the whole spectrum of the community.