restoring image on a bigger hd

Laptop installed HD 320gb.

After a headcrash i installed a HD of 500gb.

Restoring the saved image of the 320gb drive showed a working system but an unallocated space of 180gb

How can i prevent this?

A new disk of this value was created, formatted (ntfs).

Is there a manner to assemble the two parts of the 500gb to one.

Parition magic does not work in ntfs environment?