Don't buy a new one, unless you want a new one. Your computer is not broken, it is just corrupted. Once you reformat the hard disc, and reinstall windows, it will be as good as new. Before that, you may want to take it to a service that extracts data from bad disc drives and save your pictures. It might be a little pricey, but only you can put a price on the photos and other documentation that you might lose forever.
In order to keep this from happening to me, I bought a cheap portable hard disc. I keep EVERY file that I create (documents, pictures, etc) in the "My Documents" folder. That way, once a week, I plug in the portable drive, and copy the "My Documents" folder to the portable drive, preserving my information in case of a problem. Then I put the portable in my safe deposit box (backup is no good if a fire destroys it along with your computer). Also, since the portable is not always connected to the PC, it can't get trashed by a virus, and it's unlikely that it will get corrupted from a file in the "My Documents" folder.