If you have no experience in doing this, you should better not touch this. Removing and changing the cooler is really scary - if you make something wrong or forget something, you could melt your cpu...
If its the power unit that makes too much noise, just change it against a "silent" version. Also the videocard might be working as a passive cooled (no fan) version.
I had success with cleaning the fans carefully (at an NOT RUNNING!) computer with a hoover - but, be careful, dont touch anything inside the pc with the hoover etc.