Dual Monitor with vga-hdmi connection

Hi all,

Here's my setup: AMD Radeon HD 7770 video card which has a display port, HDMI and DVI input. I currently have a monitor connected to the DVI, and have a VGA monitor that I want to set up as a secondary one. I got a VGA-HDMI converter, but my video card (or computer?) is not recognizing the second screen in the hdmi input.

Does anyone have any ideas as to what to do? I'm running Win7, and when I go to "screen resolution", I press Display and select 2.Display device on: VGA, but still the second monitor is just displaying its color check thing.

Any help is appreciated!
Rich