Small businesses with fewer than 50 PCs generally have little if any IT strategy. They purchase PCs for their users, setup ad-hoc networks, and install applications on an as-needed basis. IT personnel are generally local contractors who provide assistance as needed. If something goes wrong, such as a virus or hardware failure, often the easiest solution is simply to replace the PC in question.
While this approach appears to be cost effective, in today's environment, there is another answer; a solution that provides a more cost effect approach while improving the business's ability to respond to unexpected events. It's called virtualization.