Using Dual monitors in window 7

I need some help. I use to run windows XP proffessional and could use both my monitors in fsx (virtual cockpit stretched across the 2 monitors) there was an option in my nvidia control panel to set the resolution to 2560x1024x32 and either have the monitors set one ontop of the other or side by side. Now that i am using windows 7 that option is now not there. all i can do is run it in 1280x1024x32. it will allow me to clone and stretch the display to drag windows across the 2 monitors but its not acting like one big monitor like it use to. instead of one big desktop background its 2 of the same images. When i run fsx one monitor will display my virtual cockpit and the other will go black. i can drag other windows to the 2nd monitor such as gauges and different views but i was wondering how to get the virtual cockpit to stretch completely across both monitors. ive tried running fsx in windows mode and just expanding the window across both but that doesnt work because once it gets bigger than 1280x1024x32 the edges turn black. Is there anyway to get the VC to stretch across both monitors in windows 7