I have had a Seagate drive for about a year. It is nice and solid and there have been no problems, so far. I just attached it to a USB 2 socket and to the supplied power lead and it was ready for action.
I have recently bought a WD Elements 320 giga drive to keep in the safe and use for an occasional complete copy of my data. It worked in a similar way, without problem. I want to eventually use it to make a complete 'disk image' of the HD, WHEN I get a program which does this! This takes up more room on the desk as it won't stand on its side.