As for that encrypted ntoskrnl.exe file, if you know a person who has the exact same version of Windows as you (preferably with the same updates as you), you can simply copy the file from said person on to a flash drive. You should then be able to use a bootable disc (there are plenty of them: Ubuntu, Hiren's BootCD, your own Windows (re)installation media... take your pick), and replace the encrypted file with an unencrypted file.
You might also want to run a malware scan before booting. Did I mention there are plenty of anti-malware rescue discs just waiting to be downloaded? In my experience, that's the best way to clean up those nasty root kits.