Norton Internet Security is good.

Here are some free programs.
BitDefender Anti-Virus Free.
http://www.bitdefender.com/PRODUCT-14-en–BitDefender-8-Free-Edition.html
Avast Anti-Virus Free.
http://www.avast.com/eng/avast_4_home.html
AVG Anti-Virus Free.
http://free.grisoft.com/doc/2/lng/us/tpl/v5
Avast Virus Cleaner – free virus removal tool.
http://www.avast.com/eng/avast-virus-cleaner.html

Firewall Protection.
ZoneAlarm Firewall Free.
http://www.zonealarm.com/store/content/catalog/products/sku_list_za.jsp?dc=34std&ctry=&lang=nb&lid=trial_zaFamily
Easy-to-use firewall blocks hackers and other unknown threats.
* Systematically identifies hackers and blocks access attempts.
Automatically makes your computer invisible to anyone on the Internet.
Comodo Free Firewall.
http://www.personalfirewall.comodo.com/
Use ZoneAlarm or Comodo if you normally use Windows Firewall.
Disable Windows Firewall after downloading ZoneAlarm or Comodo if it’s not done automatically.

Ad-Aware 2007 Free.
http://www.lavasoftusa.com/products/ad_aware_free.php
Ad-Aware 2007 Free remains the most popular anti-spyware product for computer users around the world, with nearly one million downloads every week. Our free anti-spyware version provides you with advanced protection against spyware that secretly attaches and takes control of your computer, resulting in aggressive advertising pop-ups, sluggish computer activity, even identity theft through stolen bank details, passwords, and credit card account numbers. If you want real-time scanning capabilities, consider upgrading to Ad-Aware 2007 Plus for real-time protection against spyware, all the time.

SUPERAntiSpyware Free.
http://www.superantispyware.com/

AVG Anti-spyware Free.
http://free.grisoft.com/doc/20/lng/us/tpl/v5

Spybot – Search & Destroy detects and removes spyware, a relatively new kind of threat not yet covered by common anti-virus applications. spyware silently tracks your surfing behaviour to create a marketing profile for you that is transmitted without your knowledge to the compilers and sold to advertising companies. If you see new toolbars in your Internet Explorer that you haven’t intentionally installed, if your browser crashes inexplicably, or if your home page has been "hijacked" (or changed without your knowledge), your computer is most probably infected with spyware. Even if you don’t see the symptoms, your computer may be infected, because more and more spyware is emerging. Spybot-S&D is free, so there’s no harm giving it a try to see if something has invaded your computer.
http://www.safer-networking.org/en/mirrors/index.html

AVG Anti-Rootkit Free.
http://free.grisoft.com/doc/39798/lng/us/tpl/v5
AVG Anti-Rootkit is a powerful tool with state-of-the-art technology for detection and removal of rootkits. rootkits are used to hide the presence of a malicious object like Trojans or keyloggers on your computer. If a threat uses rootkit technology to hide itself it is very hard to find the malware on your PC. AVG Anti-Rootkit gives you the power to find and delete the rootkit and to uncover the threat the rootkit is hiding.

CCleaner is a freeware system optimization and privacy tool. It removes unused files from your system – allowing Windows to run faster and freeing up valuable hard disk space. It also cleans traces of your online activities such as your Internet history. But the best part is that it’s fast and contains NO spyware or adware.
http://www.ccleaner.com/

ClearAllHistory – clears browser history, cache, cookies, clipboard and remove other computer activity tracks.
http://www.clearallhistory.com/

**NOTE: Only have one antivirus program and one firewall installed on your computer.
http://service1.symantec.com/SUPPORT/nav.nsf/docid/2000031316555206
"Microsoft recommends that you have only one anti-virus program installed on your computer."
Anti-adware/malware/spyware are ok to have more of.

AVG I guess

CCleaner
f-Secure antivirus
Kaspersky
Mcafee
G-Secure Internet security