Have you looked into a Home/Small Office NAS (Net Access System). I'd highly recommend the Synology family of products. I am currently using their DiskStation DS211J and absolutely love it. You can find details and my (and other) reviews for this devices at this web addr: http://www.amazon.com/Synology-DiskStation-Diskless-Attached-DS211J/dp/B0049MPQGI/ref=sr_1_2?ie=UTF8&qid=1301961036&sr=8-2. My review can found under username 'JCL69". I recommend the Synology NAS because it has a huge number features that are great for home users but it's also great as a small business oriented device. It has two internal SATA Drive Bays and 1 External USB port (for a third drive). It supports raid if you want to RAID the internal drives.
I use my NAS to store all my media files (Music/Video/Photo) and as a central repository for my data files. The DS211J NAS has a built in DLNA (Also known as UPNP) server that is just the ticket for what you want to do. You can build user accounts and setup file access permissions for all the data on the NAS and secure it by user name/account. You can access your media data from any DLNA enabled PC/Smart Phone/PDA/Game Box/TV that is DLNA enabled. All Win 7 and most Vista boxes have Microsoft's media center installed which functions as a DLNA client. X-Box 360, PS3 and Wii Game boxes have built in clients, and some TVs now include them as well. When you power up a DLNA client it will automatically browse your local network for DLNA Servers - it will find the NAS server and will display a menu on the client which gives access to Video, Music and Photo data stored on the NAS.
An example; your wife could be uploading her photos to the NAS photoshare app and at the same time a son/daughter could be watching a video stored on the NAS, also at the same time you could be listening to your favorite music stored on the NAS. I have personally had 3 clients simultaneously streaming HD movies, a net radio playing music streaming from the NAS and I was concurrently streaming audio from the NAS - All this going on at once with not a single dropout or hiccup!!! Impressive. The way it works is: populate your NAS with up to two 2 Terabyte drives (and 1 additional USB drive) and build your NAS - (set up user acct's set permissions etc) set up your backup schedule, Start Win/MAC NFS services (so you can use 'drag n drop') to copy/move files to/from your NAS using the standard windows or MAc folders. Then enable all the features you want to: DLNA server (when it's enabled it automatically creates a 'music' 'photo' and 'video' folder on your 1st physical drive). Move/Copy any video/photo and/or music files you choose from your PC's to the corresponding folders on the NAS and -Voila, they are available to any DLNA enabled client on your network.
I also store my Spreadsheet/word processing and many other data files on my NAS and that makes it available to all systems on my network 'that have the appropriate permissions set' (and the admin - "you" set those). It also will work with Win 7's Sync utility for keeping your data files up to date and synchronized. The Synology NAS also has an FTP server, Web Page server, DDNS, Photo Station, Download Station, I-Tunes server etc etc etc. So, you or a member of your family can be on the road, or at school and if you have your laptop/PC/Smart Phone/PDA - and access to an internet connection (ie wireless in a hotel room etc) you can have full access to all the data on your NAS (across the internet). From your hotel room/School Dorm etc simply log on to the NAS (via the Internet) and copy files, listen to music, etc.
I Know this is a long post but I really think the DS211J would be an ideal fit for you. Price is absolutely right, performance is terrific, support is from their own techs via telephone, setup is just short of painless (depends on how familiar you are with NAS technology) - but has a great user guide and lots of on-line resources (if you like). Nope I don't work for Synology but I absolutely love their products and I would not be without my NAS...... Joe