Software that can scan all computers on a network and uninstall unapproved software automatically

Hello experts I have another challenge for you!
                                    We have a specific laptop image which is ghosted to a users computer when they first start working for us or have a need for their computer to be re-imaged.  I work for the DOD so the software installed on the computer is the only approved software to use by DOD standards.  The problem we are experiencing is; some users are installing unapproved software (such as I-Tunes, Demo/Trial software, Xobni, etc) which will cause problems when the Govt. scans our network for compliance.  I am wondering if software exists that would scan users computers and if a program is found that is not on an approved list it will automatically be uninstalled.  I am hoping to find a solution which can be run on weekends every week which will scan all computers on the network (even remote users) and clean up the unwanted software and programs which the users installed if found.  If the user takes their computer home and does not connect to the network, then the scan would be performed in his/her computer when they logged onto the network the next time.  Hopefully, the scan and clean will run in the background with the user unaware that anything is happening.  Weekly re-imaging is not a good solution because users will lose their data.  When we setup our computers we create a C and D partition.  The D partition is to be used for users data.  A lot of Users also save things on their desktops (which is saved on the C partition).  If such software as I have described does exist, it would be even more useful if the software could also clean up the registry to remove all pieces of the removed software and programs.   We have tried denying installation permissions to users but that has caused even more problems with other things so that was not a good solution.  I hope there is software out there or a way to accomplish the weekly network cleaning I have described.  It would make life a lot easier!  Or, if any of you has dealt with this situation before and has another or better solution I am open for any suggestions, tips, information, or solutions you have come up with that have worked for you.  Thank you in advance for your help with this.  Have a really nice day!