Educators are aware that computers, both at home and in school are subjected to viruses as well as security invasions. There are number of “freeware” programs that can be used to protect Windows based computers. While they may not have as many whistles and bells as those which you can spend $50 to $100; they are free.
AntiVir Personal Edition Classic 7 (www.free-av.com) is a spy-ware and ad-ware detection program. Windows Defender (www.microsoft.com/windows/products/winfamily/defender/default.mspx) and a spam filter, SPAMfighter Standard (www.spamfighter.com) will provide decent protection.