C# app(preferably) - If file is changed, delete file with the same name in a different folder.

I want you to create an application which 1. Detects, all .avi files in specified folder. 2. Detects if some .avi file in specified folder is changed(changed name) 3. If yes, it deletes file in other folder with the same name as was the old one, but it can have different extensions(mp4,flv - only video formats like these(5 formats)) Situation: In Folder A is a .avi file with name [login to view URL], (Then this file is deleted and replaced with [login to view URL]) Application will detect, that file has changed and automatically delete file MyVideoWithCats in Folder B. but file in Folder B can have different extensions(.avi,.flv,.mp4,.mov,.wmv and .3gp), so application has to find it and delete it. Eventually it can try to delete all of these formats. ex. it can try to delete all of these Folder B/[login to view URL] Folder [login to view URL] Folder BMyVideoWithCats.3gp etc.... I need it to run in loop - so it will continue detecting if [login to view URL] has changed etc... The best language would be C# so I can modify it later. OFC I need source code. too. I need this application to run even without administrator rights under Windows. This application must run under Windows 7. It will run 24/7.