Dual Monitors setup on HP 500-319na

Hi, hoping someone might be able to help (and thanks in advance)...

I recently purchased a HP 500-319na desktop computer and would like to connect two monitors to it. Both monitors only have DVI connections.

I currently have one (working) monitor connected through the DVI connection. 

I purchased a HDMI to VGA cable for the second monitor so that I can plug it directly into the HDMI port and monitor - but unfortunately the computer will not recognise the second monitor.

Tried updating the graphics card software to the latest version, but no joy.

Am I doing something, obviously, wrong? Help!

Thanks again,

Sam