Utilizing online virus scanners
If you feel that you don’t really need to install an anti-virus or simply prefer to scan on the fly, the you might want to consider using an online anti-virus scan.
Many sites offer free online scans for your system without you having to download, much less pay, for anything. This allows you to simply go to the site, and have your system scanned for viruses and other destructive elements that have buried themselves inside your system.
The advantage of online scanners is that you do not need to install a client or program, and online scans always have updated virus lists. The major disadvantage though, is the speed of your scan, which will not only depend on the size of your system, but also on your internet connection speed.