I have set the server up on two PC's
1. Media Centre running Win7 x64
2. Windows Home Server
On 1 it is run as an application started on login and, using task scheduler on resume (closes down any running instance and starts a new instance).
On 2 it is installed as a server using srvany.exe.
Streams brilliantly to iPad/iPhones.
Unfortunately on 1 is crashes occasionally bringing up a BSOD. Mostly happens when PC finishes a recording and tries to sleep, not everyday. I can't see anything consistent in the logs to explain this.
With further testing I have eliminated AirVideo as the cause, although my observation above was accurate. Reinstalled and now its working perfectly.