It`s quite common to get a light scratching noise with new HDs ,my Maxtor had that for the first few weeks when it was new but that has now gone,however clicking noises are not good and I would run the Maxtor diagnostic utility test as well,if it passes this and you are still not happy have a word with Maxtor over the phone their customer support is excellent.
A friend of mine had the clicking sound and his failed the Maxtor utility test ,he had a replacement within 2 days(brand new drive).
Btw my Maxtor D740X does not make that metal click when I turn my PC off.