How to check if background thread is still running (on IIS 7.0)

Question

Context: .Net 3.5, ASP.Net MVC 2.0, on shared IIS 7.0 (integrated mode).

I plan to use cache-event trick to create a background "process" that shall download pages over the internet and update local database.
I plan to create a background thread, and then check if that thread is still alive (using cache-event trick). If thread dies, restart it.

Am I on a right track here?

Question #1: how do I check if my background thread is still alive? or needs to be restarted? Question #2: what are possible scenarios for my background thread to die?