whats the best way to prevent someone from getting into my files on my computer because i heard you can use usb linux and see my files
It shouldn't be much of a concern unless you have really sensitive information on there.
If someone has physical access to your device, the only safeguard is whole drive encryption. Here's a link to a pretty good paper on it:
for me the antivirus quoted by you is very good, but the experience that I had him and that ends up messing up the games due to the upload, and automatic download