After a bit of messing around I got a spare Maxtor maxline plus II 250GB (7y250m0) to work, dont know if anyone else has encountered this problem but what happened was >>
I formatted the drive on my pc using NTFS format as ya do, I fitted the drive in the VU+Duo as per the instructions at the start of this whole thread, plugged everything in and the box would not boot, just kept saying starting on the digital display and then saying VU+Duo and that was it, black screen on tv, I thought ohh no !!!
Anyway, what I done I know is not recommended, I left everything plugged in including the power, took the lid back off unplugged the sata cable from the hard drive, restarted the box and hey presto the box started right up to a tv channel (if you even think about doing this with the lid off and power connected be very very carefull you do not touch any of the electrical parts in the box or you will get electrocuted at worst or blow your box at best).
After that, I plugged the sata cable back in while the box was still booted up, and like magic I was able to then follow the instructions and the hard drive was then recognised and working, but there was just no way at all it would have worked unless I done what I done.
So I hope thats a little tip for someone who has maybe encountered the same problem.
Cheers.
p.s
I have vix 1.3