After some research I was able to figure out how to get my USBconnect Mercury 3G USB stick from AT&T Wireless working on my Windows 7 64 bit laptop. I have extracted the drivers from the universal driver package from Sierra Wireless and have posted them here for you to use. Install the software that comes with the device and then update to the drivers I’ve posted here from within the Device Manager. Included in the package below are also the Windows 7 32 bit drivers.
Sierra has posted updated drivers since I wrote this post. You can download them directly from Sierra by clicking here.