Help with computer speed, possible virus

[Krik]

So when I got home from school yesterday, I found my brother had installed a new game on my computer. I asked him where he got it from and he responded with "pirate bay", so I immediately began removing it and deleting the .iso in my downloads folder, and now my computer is running like ****, laggy, constant freezing etc. I did a scan with AVG which found 1 spyware I immediately removed it and now according to AVG I'm virus free but my computer still runs ****ty. I don't know what to do now, apart from kicking my brothers ass.

 

[Fierce Headmaster]

Kick it harder, then get a restoration point right before the install.

 

[Krik]

I stupidly, have never setup the backup system on this computer up.

 

[Krik]

Fixed it (I searched my HDD for the games name and deleted all the results) I'm locking the thread.

Nevermind it seems someone stole a GB card of RAM out of my computer.
Anyway I'm making due with half a gig of ram and a 4GB flash drive and ready boost.

Re-locked, my roomate's just so ****in' funny.