|I think the idea is that you start with a completely fresh install, which means it's clean, and then use decent security to keep it that way. OEM just refers to the way you reinstall your operating System, whether by recovery disks or by using an XP disk with your CD key.|
If you're fairly certain you've got rid of everything anyway, it's worth turning System Restore back on - it won't have any nasties in there unless your system is still infected, but it does help get you back to a clean state if necessary.
Trojans can be the nastiest, so it's worth doing as many different scans as you can find, just to be sure - TrojanRemover is free to try & does a good job, & running Malwarebytes again should remove the last bits of spyware.
"I've always been mad, I know I've been mad, like the most of us..."