First I know somethings about Computer, but I'm definity no expert, so I need your help

Yesterday I downloaded a hack for a game, (yeah I know that was stupid), it was an .exe
I tryed to run it, but nothing happened.
I kept my eye on the anti-virus to see if it detected something, it didn't,.
I eliminated the hack, a few minutes later, My anti-virus (ESET NOD32 Anti-Virus Buisness Edition) detected 4 Virus on my computer, whitch it automaticlly moved to quarantine.
Next I started suffering from lagspike of 2 seconds, every 6 seconds, which I didn't experience before.
I did a Full-System Check and It detected 2 more virus, which it automaticlly moved to quarantine, I still suffered the lagspike, so I decided to download Spybot S&D and I inmunize, and did a System Check, It detected Win32.Spynet.a, and then it closed itself, I opened Spybot again, and it detected and closed again itself,

I don't what's happening, but I want to remove it.

Help Please