Since then I only use my iPad for this site and anything 'dodgy'
...
I tried installing a couple of media programs and iTunes on to the c drive to be told I didn't have permission, which meant I had to save in 'my documents' then run the program from there.
Any advice would be greatly appreciated
OP, have you have contradicted yourself? if you're not using your PC for anything "dodgy" then no problem,
carelessness costs lives or big money.
Be paranoid.
Think about what would happen if she found out and what you want to happen, if you're OK with divorce then carry on, if not then stop.
It might be good to get the PC wiped again but this time:
Have it set so nobody can install
any programs, this means you and your wife as you will "not know" the admin pasword, this will make it harder for her to install any software. If you do know the admin password only use it when she is out of the house.
Make a list of all the programs installed and viewable in remove programs menu so that you know if anything is installed and shows up (windows update might add something).
Make a list of all the programs you see running in Task Manager so that you know ...
Install a good virus/spyware checker and update it and run it regularly, at least every week, preferably every time before you search for a punt. With a bit of luck it will spot any keylogger software.
Check where your keyboard is attached to the PC to see if a hardware keylogger is attached - they're not detectable by software.
open your browser and use a private/incognito window, history will not be kpet - however, files you download and bookmarks you make will be kept.
Remember to close the private windows first then you have a perfectly respectable browser for the world to view.
Close down and switch off your PC when you are finished.
Check your logs to see when the PC was turned on and off, you can see if she's snooping.
if she hasn't got a PC then consider getting her a laptop or something so she has no real reason to use yours.
There's more but i have to go.
At the end of the day if she's tech savvy or has access to a friend then she can find out if she tries hard enough, i'd be able to