A bit by bit ISO updater on a 18 hour routine.
Every 18 hours, my computer completely reinstalls the operating system from a
slipstreamed version I have made. It doesn't change anything else. Job done. I use AVG as a part of that slipstream, but its really unecessary.
Point all application installation folders to your storage RAID arrays or similar. Then simply use (freely available), bit by bit recorders. Create and install your favourite slip-streamed Windows install version, and then set a routine in Windows to firstly initiate the resintall on next restart at 17.5 hours, and then a restart every 18 hours (T18) unless being used. Remember, it only takes about 20 minutes for my full slipstreamed Windows 7 install to replace. Ive had longer shits.
Windows routines and cloning software (free), you can set it up, leave it to run on its own. It will install a fully functional Windows version (along with routines), with applications working. All you probably need to do is check for driver updates and double click on the Steam.exe for gaming.
After that you just set your back up to copy your personal folders, the latest patched ISO for the
clone software, and let it do its job - GAMING>
The reason im crapping on is forget worrying about viruses. Just replace the operating system regularly enough and run a standard free antivirus.