If you’ve installed Dirty Pictures, restarted Photoshop, and still don’t see the plugin listed under the filter menu, then you’ll have to get your hands dirty a bit. All that’s required is copying a file to the Photoshop Scripts directory, but the location of those two things can vary based on your system configuration.
First, locate dirtypictures.jsx on your hard drive. In Windows, dirtypictures.jsx is located at %APPDATA%\Totally Rad\Dirty Pictures. You can either enter that into the address bar of Explorer, or navigate there yourself. Typically, in Vista this will be c:\Users\<your user name\AppData\Roaming\Totally Rad\Dirty Pictures (Which is hidden by default, thanks Microsoft!) In XP, c:\Documents and Settings\<your user name>\Application Data\Totally Rad\Dirty Pictures.
This little video shows you how to perform the manual copy in Windows
***NOTE – THE LOCATION OF THE FOLDERS HAS CHANGED SINCE THIS VIDEO (SLIGHTLY), BUT THE PROCESS IS GENERALLY THE SAME ***