How to install a new antivirus software? (Such as McAfee?)

How to install a new antivirus software such as McAfee when the original computer has one installed (with 30 days trial)? I remember uninstalling McAfee once and my computer went dead (Had to reformat). How do I install one from WBB safely without killing the computer?
Thanks in advance.
Answer #1
Which version of McAfee you have installed???
Answer #2
Not sure. This is a new computer. The McAfee installed is McAfee Security Center. Not quite sure how to check exactly what version it is :/
Answer #3
You remove the trial one, go to Add/Remove and uninstall it. Then run CCleaner to remove registries, and junk left behind. After that install the AV you want.
I suggest going with freeware. A large missconception of having retail AVS cuz their better is false. Freeware work good and even better cuz no need to crack. If there are two things you should NEVER CRACK are OS and Antivirus. Rest of things can be cracked. Avira + Comodo Firewall + Malwarebytes + SuperAntiSpyware. All you need. To test cracks/keygens you use virtual machines or Sandboxie.
BTW
Not quite sure how to check exactly what version it is :
You open McAfee Security Center and then click About. It tells you what versions you are running.
Answer #4
How to install a new antivirus software such as McAfee when the original computer has one installed (with 30 days trial)? I remember uninstalling McAfee once and my computer went dead (Had to reformat). How do I install one from WBB safely without killing the computer?
Thanks in advance.
You should use a proper security program, mcafee is no good. Just putting it out there, almost 65% of the computers I fix had mcafee on them, had to undo the damage mcafee did nothing to prevent (even though 25% of infections are cause by user negligence) Buy anyways, just uninstall it run a registry scanner. Then install the new one.