How is the computer behaving now ?
This is the set up I have on my system and so far I have never had an unintentional infection
How to set up a reasonable and light security regime for your system. Apart from cryptoprevent all other elements are install and forget.
DOWNLOAD AND INSTALL ANTIVIRUS
Select Custom install
Remove the ticks from the first page for the following unless you want them :
https://dl.dropboxusercontent.com/u/73555776/avastchrome.JPG
Dropbox
Chrome
Chrome toolbar
Select Next
Deselect the following from the middle column as you will not need them :
https://dl.dropboxusercontent.com/u/73555776/avasttools.JPG
SecureLine
Grimefighter
Select Continue and allow the programme to install
Be aware that the first reboot may take a few minutes as Avast builds the virtual machine
Avast will need to be registered as this helps them determine the server load, as updates are downloaded in small bursts every few minutes each is about 2Kb
How to register
https://www.youtube.com/watch?v=uyVsLF6OwM0
Once registered open Avast
Go to Settings > General
Place a tick in "Scan for Potentially Unwanted Programmes (PUP’s) "
https://dl.dropboxusercontent.com/u/73555776//pups.JPG
PROTECT AGAINST RANSOMEWARE
CryptoPrevent install this programme to lock down and prevent crypto ransome ware.
Manually update monthly
https://dl.dropboxusercontent.com/u/73555776/CryptoPrevent.JPG
PROTECT AGAINST UNWANTED BUNDLED SOFTWARE
Unchecky
Click on the link above to be taken to Unchecky.com
click the very large Download button.
click Save
Click Open folder
Right click on the Unchecky_setup and choose to Run as Administrator
Once open click the Install button.
Then click on Finish
https://dl.dropboxusercontent.com/u/73555776/unchecky.JPG
Unchecky is now installed and will help you keep unwanted check boxes unchecked, this is a fire and forget programme 
IF YOU USE USB DRIVES
Download MCShield to your desktop and install
It will initially run a scan and show the result as a toaster by the system clock
Then in the control centre select scanner and tick unhide items on flash drives
https://dl.dropbox.com/u/73555776/mcshield%20unhide.JPG
Plug in the drive and McShield will start a scan
BACKUP AND IMAGING
It is always advisable to have a backup of your current windows set up on a seperate USB external drive
I recommend Macrium Reflect for this
I have a small tutorial here on how to use it http://www.geekstogo.com/forum/topic/345434-macrium-reflect-imaging-tool/
The restore from backup usually completes in about 20 minutes (depending on the size of your drive )
https://dl.dropboxusercontent.com/u/73555776/macrium%20reflect.JPG