I have Vista OS which had been already shop installed when my brother gave it to me as he bought a new one. It's working fine thankfully, as unfortunately I'm unable to to work through ill health and don't have the means to buy a new computer. I rely on it totally to do all of my shopping etc. and it's also my only 'social' life.
I would love a brand new machine, in fact I'd be thrilled to bits, but that'll never be an option for me and I'm certain that I'm not the only person in this boat. Please don't judge or jump to conclusions, people have their reasons.
Opera is working well on Vista, (for me anyway,) no problems at all, I'm using it now.

I was getting it too, but it didn't really bother me and it never crossed my mind that it might be malware, I just 'tutted' at it then deleted it!