There are a number of security suites available now that include a firewall, antivirus scanner, spyware scanning and a spam blocker. Some of them may not include a spam blocker but most do.
Advantages of a suite:
The different modules should 'play' well together (no conflicts). One price for everything. Updating is generally automatic with no input from the user.
Disadvantages of a suite:
The different modules may not all be the 'best' at what they do. Some may have a better firewall while others my have better virus protection.
Many of these Security Suites contain 'extras' which can include backup to offline storage, PC 'Optimization' and other modules. If these are important to you check out the features of each suite to see which offers you what you need.
One thing of note, the suite in question should have options to turn off any of the modules. This is important as a user may actively dislike one of the features and the user shouldn't have to uninstall everything to stop using the disliked feature.
More and more of the commercial products offer a free online scan. Please be aware that many of these online scans will not clean what it finds. I find this to be a deceptive practice.
Important! Check with your ISP to see if they offer free security tools. Many ISPs offer suites like Norton, McAfee to their customers in order to keep malware off their servers. These suites may be slimmer versions of the suites offered to the public, but will perform the basic security functions.