I personally keep a large amount of data on my PC, because I store digital copies of my movie collection. While it is never a problem to let others stream movies while I am using my PC, it can be a power hungry idea to watch movies myself in another room while it runs. The simple solution is a home NAS from Thecus, such as the new N7510 7 Bay NAS.
The result is also very simple by providing 24/7 access to data with minimal power use, serving up to 64 user accounts. You can use your NAS for web hosting, data backup, data encryption, application serving, HD streaming, and all with full RAID support. There is an entire battery of great features you can read about in press release below. I personally like the 20+ TB of storage in a space about the size of a shoe box.