I've been using a dual-monitor configurations forever (before XP, Win 98) and have upgraded my video cards multiple times. Of the times I have had symptoms like yours, the problem has not been the version of Windows I was currently using. But, not uninstalling the old video card driver before installing the new video card. The new video card may be trying use the old video driver configuration and that will cause problems. You may want to try uninstalling the video driver, restart Windows 7 and then reinstall the newest downloaded video driver from Nvidia.
By the way, Windows 7 64-bit has been by far the best version I've ever used and has been very stable and reliable. So, don't throw the baby out with the bath water, yet.
Also, ScatterbrainKid, FSX and FS9 was designed with the capability to use dual-monitors or multiple-monitors, that's what motivated me to go with dual-monitors. On my primary I run FSX, on my secondary I run my system monitor gadgets and Tim Arnot's Plan G, works well for me.
Darrell, I don't know if this is your situation, but I wanted to offer some help with your aggravating problem. I hope this helps.
MAE-PC9: Antec 902 \ Antec Signature 650W \ MS Win 7 64-bit \ FSX \ Flight
Intel 2500k \ ASRock E3 G3 Z68 \ Corsair XMS 8GB DDR3 1600MHz \ Corsair 60GB & 240GB SSD
MSI HD6870 1GB \ Auzen Meridian 7.1 \ LG GGC-H20L Multi-Drive \ WD 500GB, 1TB & 2TB HDD
Samsung 225BW LCD (#1) \ Sony MFM-H65W LCD/TV (#2) \ Sony SDM-X52 (#3)