They tend to not last long. In fact, if it is clicking and still working you are lucky and you should backup as much as you can somewhere else.

Probably one service I can recommend from PCWorld, is the data recovery from a failed drive and particularly clicking and "dead" ones (not seen or recognised by the PC). They use a recovery machine provided by IBAS UK a company specilising in data recovery which works with the law. They do forensic recovery (from failed, damaged and drives broken to pieces,etc) and PCWorld has some of their more basic equipment on loan. At the moment, for a failed HDD that clicks there is PCWorld for Ł99.99 or if they can't do it IBAS themselves can, they can do magic with those but at a real high price, Ł700. It all depends on how important the data is to you.

A clicking hardrive is mechanically damaged in most cases and that tends to require a specialist to open it and put it all back together (which is what IBAS does I think).