There are a million ways a computer running Windows can get a virus. Just having it connected to the internet at all is a risk in itself. I'm an I.T. consultant IRL, i know. ;p
The QELServ installer does
not contain any malicious software (viruses, etc.). Anyone with a little computing know-how can easily extract the files from the installer and see everything that comes with it, and view the batch file it runs to install and see what it does for themselves.
I suggest running and keeping up-to-date good anti-virus software.
Avira AntiVir is good, keeps itself up-to-date automatically and is free for personal/home use:
http://www.free-av.com/en/download/index.html...and I suggest running a web browser other than Microsoft Internet Explorer. Such as Firefox:
http://www.getfirefox.com/(...or Google Chrome, Opera, etc... any of them are much safer than IE)