Here's one that you can try:
http://kessels.com/JkDefrag/index.html. I use it on both of my pcs & it works quite well. It's free & doesn't have a "nag screen" or trial period. It works best if you have CCleaner:
http://www.ccleaner.com/ installed. Tip: if you get the CCleaner utility download the
slim version in the Other Builds section. The standard version contains the Google Toolbar (the slim build doesn't have this).