I am very sorry to say that Antiviruses are not enough as you could be infected with rootkits which most antiviruses do not detect. To delete rootkits with avast for example you need to restart your pc with a rootkit scan(which is included inside the avast scan area). The way it works is that rootkits can only be found before windows fully bootsup. I have been infected many times with rootkits in the past and no antiviruses actually found the threats.
I would suggest you use Zenno on a machine you do not use for your professional work or you may risk to be infected.
Once I was playing with SEO softwares on the same machine I was working with, one bad undetected trojan managed to use my filezilla(as I indigently saved the password in filezilla) credentials and injected nasty code on my 12 websites footers which in turn infected my customers. From that day, I have always promised myself to never play with Scrapebox and other things like that on my working machine.
If there is a way to change the browser in Zenno then the best option would be to use this:
http://www.sandboxie.com/
very secure as it creates a virtual area on your hd that viruses cannot come out of.
Hope this helps.
