As you probably realize, there are some costs (in time and trouble if nothing else) in maintaining a VPN server. This is probably not something that is worth doing unless you have a number of remote users who need to access your home network securely on a regular basis.
Any computer that connects to the Internet, or that connects to a network that connects to the Internet, should run some programs for general protection.
The most important category of program for protection is antivirus. Antivirus programs stop viruses from attacking your system and help you recover if you are attacked by a virus.
The leading antivirus products are VirusScan from McAfee, http://www.mcafee.com, and Norton ...