In today’s insecure computing environment, one needs personal pc protection. I’ve always had a router between me and the inet. Even when my isp (internet service provider) said I couldn’t. (Yeah right!) I’ve never had any problems with virus infections or bots that I know of. Somewhere in my travels I picked up Zone Alarm, (the free version), and it’s has served well. There are some other free alternatives as well for you to consider:

Sygate http://soho.sygate.com

Agnitum http://www.agnitum.com

and, of course,

ZoneAlarm http://www.zonealarm.com

FWIW YMMV and FAWWYPFI!