There's no getting away from the Internet these days and with online authorisations, plug-in downloads and iLok license tracking it's reasonable to assume your Pro Tools PC will be wired into the net. We've come up with one way of protecting your computer from the nasties you may encounter on your travels through the web - it's called SafeSurf. It's essentially a virtual computer, running a slimmed down version of Linux Mint that boots up and runs on your desktop when you want to surf the net. You can then safely browse the Internet and download files to your hearts content without opening a browser on your real computer. Once you're done, you can close the SafeSurf and any nasties, cookies or malware picked up on the way no longer exist. Any downloads can be virus checked and moved to your main machine via a shared folder.
However, you may want to use your Pro Tools PC online like any other computer, and that's fine, you are welcome to do so. In which case we would recommend using either Microsoft Security Essentials or Avast.com as good quality anti-virus software with a low system impact - and they have free versions. Also add the Pro Tools Plugin folder (C:Program Files (x86)/Common Files/Digidesign/DAE/Plugins) to the exclusions list of the anti-virus software, that way it will not scan the plugins one by one for viruses as Pro Tools boots up.