I don't know how common it is anymore, but it definitely was a few years back. You knew a computer was infected with everything when you saw a stupid cartoon dinosaur or something as the mouse cursor as soon as the pc booted to windows... I think it was more about what was bundled in the download from scummy websites doing the damage though, not the actual cursor files. I still cringe though if I see a non-standard cursor in windows, like PTSD-esque flashbacks...