When i turn it on it makes a clicking sound

That clicking sound MAY signal impending hard drive failure, but keep in mind you don't always get such a warning. So play it safe... back up your files now and on a regular basis.

If you want to avoid having to go through the whole process of installing Windows, all of your programs and data which is a pain in the **** and very time consuming, now is the time to get a drive imaging software such as Norton Ghost and create an "image" of your harddrive. That way you can simply recreate your harddrive exactly as it is now with one simple step. It can be a wonderful tool!