Windows 7 Professional (SP1) - replacing hard drive using image

[#1]

Hi,
I wonder if anyone can help.
I have a dell Vostro 1700 laptop (2 hard drives), originally supplied with Windows Vista Home Basic, this has subsequently been upgraded to Vista Ultimate then updated to Windows 7 professional.
I recently purchased a new hard drive to replace the main (Windows 7) drive which is showing some signs of possible failure (corrupted system file(s) meant that installing SP1 took several weeks of hard work).  The new drive was supplied with an external caddy and a basic version of Acronis True image on CD, the instructions were simle - put new drive in caddy, run acronis (boots from CD) and create image copy from the old drive to the new one, the process reported it had completed successfuly but on istalling the new drive in place of the old one Windows 7 will not boot - it suggests that a file signature has changed which could be caused by a change of hardware and that I should run the Windows 7 install disk to repair this.  The real problem is that I purchased Windows 7 for this machine as a download which runs from within Vista, I do not have an install disk to boot and attempt a repair.
Any suggestions please?
Thanks,  Alastair.

[#2]

In my experience Acronis does not work properly on Windows 7 (or Vista) to clone a drive because it does not copy the bcd file.  However you can do this manually using bcdedit.  This only causes problems if the hard disc is laid out in an unusual manner, as might be found on a Dell computer.
Surely if you buy a download copy of Windows 7 what you get is a .iso file which you use to burn an installation DVD?  If there is another different way to install Windows 7 I have never heard of it (and would be curious to learn what it is).

[#3]

Indeed.
I would assemble all the installation media (download copied from the old hard disk if required) and keys and start again, i.e. clean install and upgrade.
There will probably be a "call" or two to Microsoft along the way, but I've never known them to refuse to authenticate a genuine re-install due to disk failure.
Dell OEM media is fairly easy (and cheap) to obtain if you've lost the original Vista install and version update (or never bought them). Keys obviously are irreplaceable.

[#4]

I always use Acronis from a boot disk which gets round all the problems with Windows

[#5]

No, Oldjim, it still doesn't copy the bcd file.  With Dell this often means the link to the recovery partition is lost.

[#6]

http://forum.acronis.com/forum/17094
Now I understand

[#7]

Many thanks to all for the suggestions and kind assistance so far.
Just to explain about the 'Download', this was purchased (for my daughter's laptop) from www.software4students.co.uk, they offer some amazing deals as long as you purchase for a registered student but they also seem to have some unique download versions of Microsoft software, the download was an .img file, eventuially I got that burned to a disk but it is not bootable and ONLY works as an upgrade run from an existing version of Windows.  I was very suspicious about the prices on the site so I actually contacted Microsoft before I purchased to confiorm that this company was a legitimate Microsoft partner and not a scam.
Needless to say, I cannot find the disk I burned (I will always opt for the mailled media if I ever purchase again), I probably never even labelled it.
Thanks again for the help.
Alastair.