best practice for a independant process?

[mcmcom]

hi all,

i want to create a dll or exe projet that will run on my server and do some file maintence, however i don't know whats the best idea to do. I want the process to run independantly of the website that users will be on. And it has to copy large files from one network share to another. Should i use a .dll, or a executable file? And how can i trigger it? Can i set it to run when the session ends on my site?

thanks
mcm