I want to have dual monitors. Why isn't my HDMI connected monitor not working?

I have 2 HP 22xi LED monitors. I need to connect them to my Asus M32 computer. I have 2 output ports for monitors, one VGA port and one HDMI port. When I connect them to my monitors, only one works, the one connected with to the computer with VGA. I tried to switch the cables, but the only thing that works is the VGA. Can someone help me
Answers

Nick

Unless you have a graphics card that supports two separate monitors, you're sadly out of luck. The video card you have now has the two different ports to allow you to use one monitor or the other but it's not going to do what you want. A dual monitor card will probably run you about $200 and it's quite easy to install. Having two monitors, however, will spoil the hell out of you. =)