A system restore doesn't mean your computer is virus free now. It is still there, you better back up your files and format your system. System restore is not like you go back in the time like nothing had happened. The virus is still there and the safe way to get rid of it is to format your system.
It's not just a virus that an antivirus may identify. There are other threats that may be hidden even from antivirus that only specific programs can find. That's way a format is the best option. And sometimes they can't be identified from any known antivirus or program.
I just got rid of a
rootkit (rootkit = make your computer a zombie, what means that whoever had created it, will have total access to your computer without your permission and awareness) that was hidden in my system.
If you want to make a better test use this program:
http://www.greatis.com/security/
I am telling you all of these because this is the best advice possible, I'm sure that you don't want any one looking at your passwords when you access your Paypal or any other account. And that's why rootkit and similar programs have been created to spy on you without you know it and report all your deeds to its creator. I don't need to tell you what is going to happen next...