I have a lot of experience setting everything you want up in my house. I'm a big fan of having everything easily accessible in any location and always looking to expand my options.
You absolutely want to consider a server. Depending on your needs, just grab an old PC and a few drives. You should consider RAID but never rely on it for your data's protection. Keep the most important data on CDs and DVDs and burn multiple archived copies. Big books that hold 300+ discs are great. My aunt has over 7,000 CDs and DVDs of photos ( 10 - 360 disc cases * 2 -- onsite/offsite). I personally have more of my data on our server but I've invested in a very large server.
On your server, be very neat and clean. Try to start with your files carefully organized. Organization, in my opinion, is a huge part of usability. On your server, you should figure out how many drives you're going to use. I personally prefer having a single drive letter because that means one single share across the network. So you may need RAID to get a large, single drive. Then, here is my root folder structure on my server:
Backups, Installers, Large Scale, Music, Pictures, Podcasts, Users, Video, Web Site
Backups has an Email and Database folder. I'm using hMailServer and have our email backed up three times daily. It's just us four users and is under 500MB of total data. Database is my MySQL databases all backed up three times daily. I run several sites for different projects and such with lots of personal PHP sites, etc.
Installers has Drivers, Formatting Resources, KIP, PocketPC, Server, Workstation, Serial Numbers.txt. I keep everything that I need to reformat our computers here. I reformat our computers usually once per year in the summer. With every computer reformatted, I use Logmein and control them all. I run through all my folders and install our must-have software base. Since it's all on the server I don't have to download multiple copies of everything. It is a 3 solid day project but has been sped up significantly lately. Formatting Resources has registry files that setup the My Documents, My Pictures, My Music, & Desktop folders to point to the server. I have several other registry files to setup various programs and hide the recycle bin, etc. So on each computer/account I execute all the .reg files.
Large Scale contains miniDV video mainly and is usually several hundred gigabytes.
Music is our 100% FLAC music collection with hand-scanned 1200x1200 cover art, 355GB
Pictures is our entire digital picture collection. I organize it by year (2005, 2006, 2007) and then a single folder for each event (2007/12-25 Christmas at Home). This way I examine every photo and keep photos taken at the same event in the same folder. Plus, general information is built into the folder structure and easily searchable through MC without requiring the database.
Podcasts is just my folder for containing my ~5 podcasts I follow. I use Juice to download them on my server and have it setup to automatically call ffmpeg which converts the files and moves much smaller versions to my Web directory where I can stream them to my iPhone over the cell network with very little delay (lower quality).
Users is our complete directory for everyone's personal data. Notice the music and pictures folders are common for all users. This allows one person (me) to keep it in perfect order. I am the only one to add new music or pictures in so everything is kept in good form. Under each user account I have: Desktop, Documents, Firefox, Media Center, Sunbird, Thunderbird. These are all linked to the appropriate programs on every computer and every account. We can use any computer in our house and get our Firefox profile, My Documents, Desktop, etc. It is unbelievably cool. Firefox, for instance, stores 100% of a user's data (including extensions) in the profile folder so everything is transferred to every computer. All these folder locations are setup through .reg and other .txt files so there is not really any GUI effort...just copy and replace files or run .reg files (once they're setup).
There is also a shared folder under Users. It has Calendars, Desktop, Documents, Temp, Unused, & Wallpaper. I use a freeware program called Auto Wallpaper Changer. With a .reg file, it is automatically setup to pull images from the wallpaper folder. Unused keeps images not in use. I simply manage the pictures in there and all the computers use these same images--and change the background every 30 minutes. Calendars stores our calendars which are accessible and editable on any computer and in our kitchen on KIP (Kitchen Information Portal) which I built with Macro Express, Sunbird, etc. It shows our four cameras streaming live plus our calendar with simple keyboard shortcuts for adding events.
Video is 100% of our DVD collection...not recompressed, either...coming in at 3.46TB. The entire collection is accessible by remote through MC in our kitchen and my room. We are considering adding more units because it means no more DVD handling. Plus, the HTPCs can have a DVD drive to play CDs/DVDs and obviously this includes our pictures and music. It is opening the server's Media Center folder in readonly mode. The server uses it for serving library server & UPnP server.
Web Site is all my web sites over the years, which I host myself.