Hi Jim,

Installing 2 antivirus program with real-time protection enabled is not recommended. It might caused problem, conflict. It can affect the performance of your system.

You need to decide which one to use:
Zone Alarm Internet Security Suite or McAfee Internert Security Suite.

If you like standalone antivirus, you need to decide too whether you want a freeware or commercial version.

AVG http://free.grisoft.com
Avast! http://www.avast.com
Antivir http://free-av.com
AOL Active Virus Shield http://www.activevirusshield.com/

SOme paid standalone:
NOD32 - http://www.eset.com
AVG Pro - http://www.grisoft.com/doc/products-avg-anti-virus/us/crp/2
Avast Pro - http://www.avast.com/eng/avast_4_professional.html
Antivir PE Premium - http://www.avira.com/en/products/avira_antivir_personaledition_premium.html
Kaspersky AV - http://www.kaspersky.com/kav6