OK, if you want a PAID version, here you go.
If you want a standalone antivirus (without a firewall) I would recommend either:
Kaspersky Antivirus 6 (the best one out there, but expensive)
Bitdefender Antivirus 10
Norton Antivirus 2007*
*Note that Norton is notorious for system drag and uninstall problems, but I've read that the 2007 version is lighter than 2006. It DOES do it's job quite well and have been around for a while.* Many of the expert reviews on the web give Norton high marks.
If you're looking for an all-in-one security suite (antivirus, firewall, anti-spam, etc.) you can't beat ZoneAlarm Internet Security Suite. Make sure you get version 7 as this version uses the Kaspersky engine for it's antivirus component (a good thing, see above). If you have Windows Vista, use the newest ver. 7.1. If you only have XP, use 7.0 You can use it FREE for 15 days, fully functional, without obligation.
Norton Internet Security Suite 2007 also received very high marks out there from reputable reviews, but the average user has complained more about this company than any other. You make the choice.
Good luck.