Windows Service with Impersonation

I am looking for small program to work with Windows 2000/XP/2003 environtment as a Windows Service. While having all other windows service features, I need it to promopt for a username and password (created and maintained seperately by this program) right after a user is logged ON but before anyother program or desktop is shown. (I have seen this kind of work while I install Antivirus etc). Any users must be able see their desktop "Only after entering the username and password of this utility". In otherwords, it is a another layer of protection to login to Windows. I am also looking for a way to ERASE some encrypted files COMPLETELY based on the username we enter here in the utility. Please note that those files are encrypted by windows and acess security is given ONLY to my windows user account. So, this utility must be able to impersonate my windows account to achive this task. (My windows user name and password will be given to this utility). FILES TO BE DELETED ARE LOCATED IN SEVERAL FOLDERS AND TOTAL SIZE IS CURRENTLY 10Gb and MAY GROW IN SIZE AND NUMBER SOON. I DO NOT WANT OTHERS TO SEE THESE FILES. SO, I EXPECT YOU TO DELETE THEM BEYOND RECOVERY AND VERY QUICKLY. THIS DELETING ROUTING MAY BE DONE USING ASSEMBLER OR VC++ DLL AND CALLED FROM INSIDE THE VISUAL BASIC PROGRAM YOU WILL DEVELOP. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform Windows 2000 Windows XP Home/Pro Windows 2003