A stitch in time saves nine. If your virus scanner offers free updates via the Internet, make sure you take advantage of them. The free updates include detection software for viruses that may have surfaced after you purchased your original antivirus software. Virus detection software needs to be updated consistently to detect these new infections as they are discovered. Don't take candy from strangers.
People download software off the Internet all the time.
And most people share data files across networks and on floppy diskette. It's important not to trust any file that comes in from a strange source. If you receive an unexpected file, delete it immediately and then scan your system. Take note of any mysterious messages or changes to your system while or after deleting the file. Also, make sure you set your virus detection software so that it automatically scans any new files that are copied to your hard drive, either from media such as diskettes or when downloaded from the Internet.