vundo y and stopzilla

Before I go through the steps in "read first", I'd like to ask a question or two if I may.

I have Avira, free version, installed and ran a full scan 2 days ago, and it found nothing.

Knowing that one of my hotmail accounts has been sending out spam, I installed then ran the adware program stopzilla, which found 2 trojans (Vundo.y and one other I didn't write down) and 7 bad cookies. As you would know, stopzilla won't quarantine or delete without handing over money, which always makes me leery when something finds a problem I can't see and then wants credit card details. I also get suspicious when I can't stop or minimize this install, so I deleted it). I then found numerous complaints about stopzilla here; http://www.complaintsboard.com/complaints/stopzilla-c168549.html
so I downloaded and tried ad-aware free version, which found just three bad cookies and no trojans. Not convinced, I download and ran iobit security 360, which is how I found this place, and it found just one more cookie, no trojans.

So, is stopzilla a scam and should I worry about these trojans after the other three checks found nothing?

Phil.

 

just to add, I also tried the current version of spybot S&D, and that found no trojans either.