Hi, My name is ***** ***** I'll be helping you today.
If it were me, I would use a DVI dual link splitter and then connect each monitor through the two separate DVI connections. You could use HDMI and DVI combo, but if your video card supports dual DVI, then I would split it. Unless you want the audio feature of HDMI. Then of course you need to make sure you have the right drivers for your Video card to get the best performance. The Default Windows drivers are generally inadequate for dual monitor support. Give me a few minutes and I'll point you to some recommended cables.
In the mean time, can you answer a few configuration questions:
What make and Model of video Card to you have?
What version Windows are you running?
I misspoke on my first reply. You indicated a 24pin female, therefore you cannot use a dvi splitter unless the card supports it. So instead you will want to use both the DVI connection and the HDMI for the second monitor. So it sounds like you have it connected correctly. Unless you want to convert the HDMI signal to DVI, which I've provided a few choices below. As far as your DVI to DVI connection, any standard DVI Cable should do the job for you. Just match up the male/female combination as needed.In my opinion, http://www.monoprice.com/ is by far the best supplier of cables and other computer/video accessories. They have just about everything you will need
Here are a few suggestions:
Be sure you have the latest Nvidia Drivers installed instead of the default Microsoft drivers. I also highly recommend a program called DisplayFusion http://www.displayfusion.com/. It has a lot of great tools for managing dual displays:
Hope that helps.