Internet Download Speed Issue

Hey guys,
Recently my internet has been extremely slow, but only on my computer. I built the current PC I am using and I also built my previous one, which my little brother uses.
His download speed is fine, average at 5.85mb\s, my partners laptop download speed is averaging at 2.0mb/s(thats with a 2 bar signal as well), yet my download speed is this https://www.speedtest.net/result/2669099451.png
That's the thing I don't get, my PC is a lot more powerful than my previous one as well. I have ran Virus scans though AVG, Disk Clean ups, Defrags, Malwarebytes scans for Malware yet that doesn't seem to help at all, although I got rid of 6 Malware issues which was good.
I have re-installed and updated my Ethernet drivers and that also hasn't done a thing. I have had a look on Google, went through a lot of forums and tried out different approaches to this without success so any help would be extremely appreciated.
I am connecting with a Network cable via a Netgear Wireless N+ Modem Router - Model DGN2000
I have tried running safe mode and the internet speed is still the same.
I replaced my cable with a new CAT 6 Cable and also tried switching ports on the router which also didn't work.
Last night I disabled my windows firewall and my antivirus and then ran speedtest and the speed got up to a maximum of 2.6mb/s, which is a big change from 0.36mb/s. This didnt last long though, but it did stay the same after I turned everything back on.
I used to use AVG but deleted that and installed MSE, once I scanned with that I found a Java exploit virus and a virtool win32 obfuscator xz virus. I removed the Java exploit but failed to remove the virtool win32 obfuscator xz. I decided I would try and get rid of its origin, some game ISO's I had, which are now deleted. But I think this virus is still lingering and messing with my computer. I dont know if it is directly causing issues with my internet, but the speed of my internet feels like its slowly degrading everyday. I have been through some other forums about this virus and I tried to follow the great advice of Jacee but I cant download any of the tools to do the job that she is asking. I am almost at the point of re-installing Windows as this getting extremely frustrating. All your help will be greatly appreciated and I look forward to your replys.

Hey Roderunner, thank you for you reply.
Interesting, because my alternate computer(older hardware), which my brother uses, does speedtest.net tests at 5.6mb/s. He is also wired to the same router. I did ring my ISP and they are doing maintenance in the area. What I don't understand about that, is if that's the reason my internet is being absolutely shitty, than why are none of the other connections(my alternate PC, 3 wireless laptops) effected by this? Extremely frustrating.

So apparently Google Public DNS is 400% faster than my current one, how do I go about changing that?

Alright, done. Internet speed has risen to a steady 1.6mb/s which is acceptable but not the best. My ISP is undergoing maintenance in the are and is causing a bit of drama. This will go on for a couple months, might have to change. Thanks for the help Roderunner