Generally any antivirus software will suffice, though it is highly recommended that you select an anti-virus system from a reputable company that has an established reputation. Most antivirus software includes antispyware, and is sold on an annual subscription basis. Macs are not immune to viruses, so antivirus software for Macs is highly recommended. Please be sure to update your virus definitions weekly, if not more often. Most software will automatically perform updates on a regular and frequent basis.