
They will only get deleted if you initialise/format the HDD.
Check that the HDDs are the same physical dimensions.

In fact swapping HDD's between boxes is the very same as flashing a box and leaving the HDD in place.
Normally the internal HDD will be auto-recognized as such and be mounted as HDD; if this would not be the case you can use the ViX-mountmanager to correct that.
As Abu already said: as long as you don't initialize the HDD the contents will not be touched.
