Viral infection - rootkit?

I'm running windows 7 premium.

So, I'm almost positive that I have a viral infection on my computer.
I've been having some run errors in games, some system instability with the occasional blue screen of death, and general lagg / stuttering. I got a virus back in November from a game torrent my boyfriend wanted me to download with him. He was lucky enough to be able to perform a system restore and wipe the virus off of his computer, but I, however, was not. It took a while, but I eliminated a lot of viruses using Malewarebyte's anti-malware and microsoft essentials.




So, the processes Atieclxx.exe, csrss.exe, and winlogon.exe (Vital windows processes; prior to me wiping my harddrives my tablet drivers were also reacting the same way.) When I try to stop the process, (which is normally a stupid idea since they're vital), I get the access denied message, so I'm assuming whatever is in my system is blocking this from happening. Also, if I right click any of those processes and try to open their file location, nothing happens. Literally, zilch.

So, after dealing with this for a while and not being able to solve any of the problems, I wiped my harddrives and reinstalled Windows 7 from the disk I recieved with my computer. Even though I completely wiped the harddrives, the same processes were still on my computer after installation. These viruses also block access to certain folders, though I don't remember which.

I tried looking up registries to change to fix this particular virus, but they were all either fixes for windows XP or I just couldn't function well enough with regedit to find the registries, (I have little experience in that area).

So, I'm wondering if this problem is causing an overall reduction in CPU / system performance. I've been having strange problems in my games lately resulting in odd FPS decreases like maintaining a constant 50 fps regardless of whether or not my graphics settings were at max or lowest possible or not, (in diablo 3).

Any help or suggestions?
Should I buy a new harddrive and windows disk?
Could someone help me with the registries?
Can anyone think of another reason why I'm having these problems in my games?
Thanks.