Would you be willing to run a dedicated home server+storage for this purpose, e.g. Dell T20 or Lenovo TS140 ($300) + 4-6 disks in RAID1 config? It could run ESXi / KVM / Xen, e.g. FreeNAS in one VM, knowledge base in another.

For UI prototyping, some options are Qt/Webkit, a browser extension, or http://breach.cc/