You ask good questions. Let me try to answer them.
That is a myth. Free programs are often as good as paid ones and sometimes even better. This is a speculation mostly promoted by resellers to bully unsuspecting customers into buying their products.
As I said, it all comes down to your personal preference. :)
Yes ZoneAlarm was found to be heavy on resources during our testing. Also, its detection rate, though good was not up to the par with the others listed and so it was discarded.
No, we would never force our own preferences on the users. All the security suites listed were judged on the basis of their detection rates and ease of use. Another important criteria was their interference with other programs. ZoneAlarm failed miserably in this field because its Firewall created a lot of network problems. We also reviewed the past threads to see which programs did a better job than the others. :)
I am not sure what's that supposed to mean. Computer specifications of a user are secondary. If a program has good detection rates, its ability will not be hampered on slow computers. Besides the usage will be the same too. Its just that slower computers will experience a lag because they have lesser resources than their higher counterparts.
Hope that answers your queries.
-- Goku