Finally manage to get WHS installing.

The PC that has been giving me loads of grief succumbed!
Admittedly the pc is a bit old but should be ok for WHS specs but everytime I tried to boot off the WHS dvd (or any other tool using WinPE) the machine would hang. I took the hard disk out of the machine, put it into my live pc and installed WHS on the hard disk successfully, tried putting it back in the original case and the pc would endlessly recycle :-(
The next thought was to flash the bios to see if this would improve things. Previously I had search for the Bios (ASRock K7S8X) and hadn't found anything, but this time I found a bios update from ASRock's website. The trick was getting it onto the pc as the machine had no OS and all my other machines have no floppy drive. In the end I copied the files onto a usb thumbdrive, booted into BartPE and copied the files to the floppy. Then booted from another techie cd that gave me a dos prompt and I was able to update the BIOS with asrflash.exe
A restart and check of bios settings and I tried the DVD again, and this time it is installing ok.
Now to go and close the various bug requests I have open with Microsoft and other Beta software companies.