jimv7 - I nearly did what suggested by I thought I'd gone for a simple update of the OS but instead got a completely new installation wiping out ALL my existing data and settings. Then went back to the drawing board - see later.
pj123 - I'm wary of trying xxcopy having seen some cautionary threads here. The reason the new drive was known as E: is because I had already formatted and was using for backup purposes. But, I think that is probably the main reason for it failing to boot. ie only disc in drive but its called E:.
In the meantime I've been watching a PowerQuest video about DI7 and on closely watching the details I noticed that the target drive was fresh out of the box ie unformatted. So I've just deleted the partition from the new HDD - so its got no name at present - and I've copied my master to it.
I'm now about to switch the drives (and jumpers) and see what happens next.
I'll let you know.
If I have any problems I'll go on to follow Jim's suggestion.