If I may make a couple of suggestions.

The latest Zone Alarm firewall,

and the latest AVG AntiVirus.


Those are both free editions, if you're looking for commercial software I suggest looking through:

Zone Labs (Support for Zone Alarm products AV and Firewall protections)


F-Secure (AntiVirus and Firewall)

and/or

Symantec Software (AV and other protections)


The Firefox browser is very reliable also, check GetFireFox.com or click the link in my signature.



EDIT: Forgot AdAware (SE)

Good for keeping the ad/spyware off your new PC.