migrating forms app to web app

I have a crawler application that finally runs decently and was considering creating a web interface to run on the front end. Some have advised that if using asp.net and implementing background worker threads would not be a good idea so I was wondering what input anyone here would have.
My app runs a background worker to run searches on urls while the main can do other functions like run queries etc. I have created a web form for the app and it seems like it may work but not to sure.