chkdsk /r would have the same effect as a full format.
If it is SATA/eSATA drive you can use SpeedFan (
http://www.almico.com/speedfan.php) to check the SMART attributes.
As far as stress testing, there are probably programs to do it but I'm not sure. Personally I think it is unecessary.
I've only had 1 drive that was bad from day 1 and I caught that from the format (drive would start clicking/lock up when it got to a certain sector).
If you are going to be storing anything that is not easily replacable I'd recommend getting a second drive for backup at some point. Definately backup your critical files somewhere regardless.
I backup all my files to a secondary computer each week and I backup my critical files to Amazon S3.