Actually I made a mistake with the final "Optional" part of the guide.
As I learned the hard way.....what happens when you use xplorer360 to copy the files back over....They DO copy over BUT....xplorer doesnt see the true partition 3 thats on the drive and thinks its empty, instead its as if it sees what it thinks it is. As a result....when you copy files over to the partition with xplorer360 - and then put it back in the 360....the files show...BUT the total size available has reverted back to the old size.
So I reformatted the drive in 360 and that partition showed up as fine again with full space.
I then did try using FatXPlorer among other xplorer360 alternative programs - but they're all very slow to transfer large amounts of data - and sometimes come up with error messages when trying to transfer..... Do seem fine with small transfers however but if trying to dump a load of data then seems very tempermental (to me at least)
Soooo...the easiest and fastest way to get the data back to 360 is the manual way with a USB drive and copying it in xexmenu. (I can't edit the first post unfortunately)
Soooo..
16. Launch Xplorer360_extreme2, click Drive | Open Image | then select your original hdd image file.
17. Click on Partition 3
18. Highlight all the files in partition 3, then right click and choose Extract. Select a temporary folder on the USB Drive and let xplorer360 extract all the files, content, xbla titles etc to your USB Drive
19. Close Xplorer360_extreme2.
20. Load up 360 (with the new hdd connected) and plug in the USB drive to one of the ports.
21. Launch xexmenu from a CD
21. Within XEXMenu, browse to your temp folder on USB drive, then select Copy to the first folder. (eg $SystemUpdate )
22. Navigate to the root of the main hdd for xbox 360 and select Paste.
23. Repeat 21 and 22 for each of the main folders
All your content should now have come across with no problems. (This time

)
You generally should only have 4 folders.... $SystemUpdate , $TitleUpdate , Cache, and Content.
Be sure to only copy from them folders....it's not the end if you don't - but inside the Content Folder is likely to be lots of subfolders. If you copy from the whole of the Content folder it should copy every subfolder too......whereas if you tried to do each individual subfolder, there is no way at the moment in XEXMenu to select multiple files so could take ages
is this part supposed to take ages or is it just me because i left it on all night and it did not finish
is there a better way of doing this? Also the 640 GB hard drive i have has been opened in xplorer360 with 3 partritions. But when i copied the content folder from the image to partrition 3 it did not finish all the way and i was stuck with only 109 GB free is this because the drive is not reporting correct size?