O&O Defrag is one of the best out there. It is not, however, free. It has a 30 day trial to try it out.
To give a brief description of performance increase, I have Half-life 2 on my Ferrari 3200 laptop and load times are a pain; but after using O&O, load times are literally 20% what they were.
Hope this helpshttp://www.oo-software.com/en/index.html