As a working Computer Tech, I have to provide my customers with the best Security Software Package.
So I give them the same FREE software that I use on my own PC to keep it virus and spyware free.
I start off with AVG 2014 FREE and then supplement that with Spybot Search & Destroy and Spyware Blaster.
Some people are just too lazy or too stupid to actually RUN any security software, so it's good that AVG can be set up for totally automatic operation. But it doesn't come like that.....you have to go into Options > Scheduler > and turn on the daily scan and set the times for the scans and updates.
Those are just the base. Added to that, would be Malware Bytes and Super Anti-Spyware.
A lot of improvements have been made to Windows 8.1, so it will run much older software.
I'm personally running one game that I bought on a single floppy disk, back in 1990 (or there abouts).
It's a 16 bit program, but it runs on 8.1 just fine, with 16 bit Compatibility enabled.
Every program that I normally run on XP-Pro, also runs just fine on Windows 8.1, so there's no need to look for special programs.
If you have any favorite programs that you've used in past years and on past OS's, there's a very good chance that they will run just fine on Windows 8.1. Try it! With some, it may be advisable to "Run As Administrator".
Cheers Mate!
TM