Actually, you have a few options. To simply see folders and files on your PC (similar to Windows Explorer), and to transfer between the N7 and PC, as well as open some multimedia files directly from the PC for viewing on your N7, use a file manager with LAN capability. I use ES File Explorer (free) and Solid Explorer (nicer interface, but costs a few dollars). Of course, you have to set up proper permissions on your PC to allow access, something you may have done already if you have multiple computers on your network.
Another option is a remote desktop application. This let's you see and operate your computer directly from the N7, even outside of your local network. This includes the ability to transfer files between your computer and the N7. Setup is a little more complex with these apps, and they cost more money than most apps, though free ones exist with certain limitations. I used one called Remote Desktop Client that worked very well, but couldn't justify the $14.95 price tag for the limited amount of time I would use it.