fresh install with new HDD

Just simply reinstall, and it will activate automatically (skip any key entry).

In rare event it fails to activate, you can use your old windows key if you install version 10586.

Note: good plan to make an image backup of current install just in case things go pearshaped.

reddwarf4ever said:

thanks
will give it a try....will keep the old HDD as a backup anyway.....
fitting to a DV 6700 laptop I assume there is no HDD size limit

Assuming laptop is eufi based, no limit. For older legacy bios limit is 2.2TB without special drivers.

If there are many programs installed or files saved on the old hard drive, better clone everything to the new HDD. This will save you some time to reinstall everything. Use Macrium reflect or Easeus todo backup freeware to clone.