Okay, follow CyberLink's spec recommendations. I know they've upted the minimum as the capability of computers has progressed.
The area you need to look at closely are.
1. Unnecessary software background access to the internet
2. Necessary software access.
Make all updates of Anti-Virus manual actions - never auto-update as it will interfere with rendering/editing etc.
Make the Firewall block nearly all Software background access for updates - there are exceptions which you'll have to decide are okay. I would have your Firewall ask you each time... For example Mozilla Firefox (web browser) needs access to the internet and updates are useful and apply when you initiate the program.
Restrict cookie and up your security settings in the Firewall.
The aim is to not have any background intrusion or programs running which will/could upset video editing AND will make your computer more secure.
I've shut down and deleted MSN from all systems here.... it is an intrusive background running program.
I do NOT allow PD access to the internet without referral (SmartSound Music files are the main need for this program to have access).
Common sense rules...If it ain't bust why fix it!
I've written in general terms here and this is only my opinion.
Dafydd