Read the docs... or install it and test it.
If its an important machine... then read the docs.
I installed software on a new server (wasn't important, as it was just in setup phase) and it crashed the 2k3 server all together. It was outpost firewall. I had to reload the whole thing. Recovery, last known good, etc couldn't recover it.
A good setup that I would recommend would include the minimum of Norton SystemWorks which includes Norton Go-back, a combination of Ad-Aware which can be downloaded through lavasoft, and Spyhunter which can also be downloaded, the problem with spyhunter is that you have to go into your registry and delete any parasites yourself but it will tell you where they are located. I'm always looking for new programs that work well but theres alot that arent that good, infact I downloaded one named BPS spyware remover and it was using all my PC usage and it was a troublesome program. "By the way, is Stardock some sort of parasite because ever since Ive had it, my PC has been acting up, I actually cant download anymore and it seems like new bad things are happening everyday. I cant uninstall stardock either.
Kaspersky Antivirus (KAV) is best choice and its engine is used by many other vendors.
Not so known in USA due to low marketing activities, but...try it for free for 30 days and you will see the difference