Windows 7 error 'this is not a genuine copy of Windows 7'

I would think this happen before you reinstalled windows. But if you do not feel safe. Run your antivirus program and a couple spyware programs to make sure. The best you can do now is to make sure you keep a good virus program installed. Plus a couple of good anti spyware programs installed. Plus keep your firewall on If you are running behind a router all the better. Make sure about websites you visit and email you open.

Yea I think your right, I have AVG(Free version) is this enough? with Malware bytes and ccleaner.

Any other recomended payed or free security programs?

It should be. I use Superantispyware free one. Along with MalwareBytes. Because some times what one dose not pick the other might. There are other spyware programs you can try to such as Spybot Search and destroy, Spyblaster. These are pretty good programs to. You could also try Avast as your antivirus. It ranks better the Avg dose

But is it bad to have avg and Avast installed on the one machine?

Not such a good Ideal. You really only need to run one anti virus program. Either AVG or Avast