Acronis True Image is by far the easiest, and you can download a 30-day trial which should let you create an image and then copy it
The other two are a bit more idiosyncratic
if the existing hard drive is a Seagate or Maxtor you can download a fully functioning free version from the Seagate website
Some of the other drive companies also have a similar deal (Western Digital for one I think...)
the Seagate / Maxtor version - DiskWizard - is here
DiscWizard | Seagate