First, find the Antivirus you feel most comfortable with using. Look at it's Pros and Cons, and it performs on your system. How it detects malware, and whether you need to interact before any actions have been taken.
Next, decide which Firewall would best suit you, would you be prepared for pop-ups from either of the Firewall software. How about knowing that Comodo Firewall has HIPS (called Defense+) which can be talkative, and it also uses a Sandbox to isolate (?) unknown files.