DLNA usually works the other way, i.e. the hard drive (like my own Netgear ReadyNAS NV+) can serve DLNA clients with pictures. So my DLNA client TV-set can display images hosted by the ReadyNAS. My 7D with WFT-E5B can also work like a DLNA server, thus allowing the TV to show images stored on the camera's memory card.
The 7D/WFT-E5B can store images on a harddrive, as you shoot, or later, as a backup, but you have to connect the harddrive via cable to the USB port. This functionality isn't available over Ethernet.
The 7D/WFT-E5B has two possibilities for pushing images to a harddrive as you shoot. One is connecting to an FTP server, with the 7D as a client. The server built into Windows XP professional works, for example. The other possibility is running EOS Utilities on the receiving computer. In either case, an independent drive, which just shows up in a network as a Windows device, will not do. It has to have an FTP server, and it has to be one the camera likes. My 7D doesn't work with the FTP server in my Netgear device. I don't know why.
Besides, last time I looked, only the 1D-series with network adapters (or the 1DX) and cameras with add-on Ethernet (like the 7D) supports FTP transfer anyway.