Anti-malware software can easily be configured to have minimal impact on the system, and can be very useful for those who are uncertain about what malware threats mean and question their abilities to follow through on instructions to manually remove them.
For people who are not too technically savvy I recommend installing a basic scanner such as Sophos, ClamXav, or iAntivirus, and then configuring it to only do a scan of the system once a month or so. The scanner existing on the system will not hurt anything or slow it down, and as such can be used to manually scan systems on-demand instead of continuously scanning on-access (which can slow down the system).