Ok heres what I use and Ive never had a virus(well Ive had one but it was found and deleted straight away)
Firstly, for your anti virus download avast 5 home edition . Its free and the newest version of it has just come out. Its been compared to norton and mcafee and it uses less ram and is much better.
avast has inbuilt anti-spyware so you wont need to download a seperate anti spyware program.
Once avast is up and running go and download smart defrag. this program defragments your hard drive for much better performance. (run smart defrag overnight because it can take a few hours)
Next download ccleaner( I run ccleaner everyday0 it only takes a few minutes and is great.
The last thing you will want is a registry cleaner, if your willing to spend some money get regace, but if your not willing there is a great registry cleaner called comodo registry cleaner.
after you have all of these run a full system scan with avast, defragment your hard drive with smart defrag, run ccleaner, and run comodo registry cleaner.
this should optimize your computer greatly and help with your virus problem.
avast home edition- https://download.cnet.com/Avast-Free-...-10019223.html
smart defrag- https://download.cnet.com/Smart-Defra...-10759533.html
comodo registry cleaner- https://download.cnet.com/Comodo-Regi...-10895685.html
reply back later and tell me if that helped :D