I would steer clear of dedicated hosting TBH. The overhead is way too much - can you really be bothered to patch everything constantly yourself? Are you a security paranoid who can spot rootkits which have been dropped on there etc etc.
Most of the stuff you are talking about can be managed with something like Drupal.
Do you really mean streaming audio and video, or just having it for download?
If you've got your heart set on having a dedicated box, I'd look at getting a static IP address at home and setting up your router to forward requests to it - if you're only prototyping with a few users - that could be the way forward.
One final point would be that you don't need anything even vaguely approaching a Xeon for serving. You'll most probably be using a Linux distro and Apache which will happily run with spare capacity on an 800Mhz P3....