Confused. What anti-virus should I use?

[Ink]

Due to the reason Microsoft having ceased critical and extended OS support for Windows XP SP3, I strongly recommend either switching to a Linux distro such as, Ubuntu or Linux Mint.
http://www.ubuntu.com/ or http://www.linuxmint.com/

Alternatively, I would consider buying a new PC that is running Windows 8.1. A new, modern PC will have better hardware and the power to drive your PC needs. No more slow downs from old OS/hardware.

FYI: Windows XP SP3 is now vulnerable. You'll receive no further security updates or patches to secure your Windows XP computer.

 

[knownothing]

I've run defrag and diskcleanup and it seems a little better now still get unresponsive scripts though and I still haven't decided on an antivirus and still got no sound been into drivers etc and it says they are all working.
Not sure about a new computer, I know windows xp is unsupported now so what's the worst that can happen?
I use a friend's laptop with window8 and i'm not fussy it has no spreadsheet and it's not as nice for documents as MSword not fussy at all.
I'd really like to stick with this PC if it's not too dangerous already got and old pc sitting here, it came in very handy though when I had a virus I printed out instructions and got rid of virus on my own (chuffed with that) then I got to this forum and Jack helped me clean up.- Thanks again Jack.
it must be frustrating when us knownothing's ask for advice to you eperienced users. I know a bit more than turn on and go to websites but not advanced stuff so thanks for patience and help.