After a bit of looking about I finally got a one of these off of ebuyer

http://www.ebuyer.com/414257-adata-640g ... -640gu-cbk
an ADATA 94 CH94 640gig, purchased mainly on cost (40 quid) but also well reviewed and 640gb was about what I wanted as well

So I thought I would try write my image to a Hdd
First thought was Mevis, excellent Xp but the links were down

Then I thought I would try xbmc os 0.9 which had failed with a login prompt on a usb stick but at least I had a copy of it.
I used win32 disc imager 0.7 and my new hdd showed up straight away (so no hot swapping as previously documented needed)
After writing I plugged in to my Joggler and switched on and it booted up perfectly, nice and smooth in operation too...
Result

Next I need to find a copy of Xp to try as this ran quite slow on my usb sticks and I am interested to find out how much my new toy speeds things up.
An idea of how small this thing is, is that it fits comfortably inside the metal stand of the Joggler.