Neat simple tool that lets you check your disk performance from ‘Crystal Dew World‘.
There are couple of other tools on the site – not tried them though. All distributed under modified BSD license.
CrystalDiskMark – http://crystalmark.info/software/CrystalDiskMark/index-e.html
(Note: install also prompts to install PC Matic – PC Pitstop free scan which is another 3rd party program to test overall performance and is not from CrystalDiskMark)