Well, when we are discussing about firewall,antivirus,antspyware,etc the usual suspect is always Windows.Right ?
So, for Windows:
I have been using Zone Alarm Internet Security since time immemorial.
They are now known as CheckPoint.
But, neither their Antivirus nor their antispyware are so good, so use some other AV like Avast, which high detection rate too.
Also, it boils down to personal choice too.
Do you want to be nagged for every incoming and outing request?
If the answer is yes, Comodo and CheckPoint are best and they don’t consume too much of resources.
Else, you can use AVG; they seem to have garnered a lot of users lately.
If you don’t have commi-phobia, you can also use Kaspersky!
A straight NO-NO for Symantec and McAfee, they, politely put, suck!
For, Linux:
I use iptables, they seem to be secure and I guess they are.
For, Mac:
I use NetBarrier X5, they are quite good.
Thanks