Unfortunately nothing is straight forward. There are always many versions and revisions of all software out in the market place. Identified problems may only apply to a specific revision clashing with a specific revision of something else.
PC and Internet security threats are ever moving goal posts. To counter attack you need to move with them especially after a major change such as SP2 to SP3. This months top antivirus product could easily be next months disk filler.
All singing, all dancing products should be avoided. It is worth the extra effort to find firewall, antivirus and anti malware packages that work together.
Firewalls
http://www.matousec.com/projects/firewa ... esults.php
Antivirus
There are as many reviews on anti virus as there is products. Problem is very few are independent. Avast is always up the top somewhere and the home version is free. It uses various different detection methods so can detect Viruses and other Malware.
Anti malware
Avast finds most but Anvir (free) is also very tenacious. Malware changes more rapidly than any threat so keep reviewing and change if necessary. The databases must be kept up to date with regular updates or they are useless.
EULAs (End User License Agreements)
A legal requirement to have it but the content can contain all sorts of nasties. If you are installing any software that is not mainstream or is free or is shareware then read it before pressing the agree button.
E.g EULA's text "the software can go online at any time and upload all data entered on you PC since the last upload." You normally wouldn't read this and go on to press "I Agree".
The site below contains the interesting, and maybe true, story of a guy who earned himself $1,000 just for reading the EULA. Rumor has it that the promise had been made 6 months before it was eventually claimed.
http://www.pcmag.com/article2/0,2704,2243185,00.asp