In reply to FesteringSore:
Can't help other than to confirm that my Nexus 7 is automatically recognised by my Windows PC. On first time connection it installed the drivers and then the Nexus was visible in Windows Explorer.
Only sneaky thing is that you need to swipe down on the Nexus settings menu and change 'USB for charging' to 'File transfers' if you want to access files on the Nexus.
Suggestions - try a different USB port if possible, try a different USB cable, if you are trying to connect through a USB hub, try a direct connection to the PC.
BTW - surprised you didn't take advantage of the free upgrade from Win 8.1 to Win 10 - it was a huge improvement.