Can I concur with woofgang concerning Western Digital. I bought one a couple of years ago and the 'clicking' sound they apparently all (or majority) make drove me potty.
I am in no way connected to them but would recommend Hitachi Touro
Amazon.co.uk User Recommendation
I have 2x2TB sets which are basically on 24/7 and have been since getting them. Absolute faith in them.
I know this is twice the size but it is only about £15 more than the 1TB and has its own power source