It is proper Netiquette to update software regularly. Do check for updates.
Anti-virus software is not the only software that needs to be updated to prevent spyware from infecting your computer. All programs that update include security patches in the files they update. Keeping your software update protects you and your network.
Many people use automatic internet updates to keep their software updated. Operating systems and web browsers are prone to attack, which makes updates for this type of software more important. Windows has automatic update settings. Google chrome has them. Firefox does as well.
Update software regularly because out of date programs are vulnerable to attack.