While Vista drivers
will work most of the time, they aren't always compatible with Windows 7. I'd suggest that you contact the customer service of the manufacturer and ask them whether or not their hardware is able to be used on Windows 7.
In the meantime I'd suggest that you try a few more options.
A) Attempt to install the same drivers without using compatibility mode.
B) Attempt to install the same drivers using Windows XP compatibility mode.
C) Attempt to install the second set of drivers
with and without using Vista compatibility mode.
Make sure that you completely uninstall the drivers and disconnect the device between each instance. You may also need to restart your computer after each installation and uninstallation.