IIS - Other - Long running processes in IIS

I have a web app (asp.net) for which there are a number of processes that could potentially be long running. For arguments sake let's say these could be 1hour+. I don't want these processes to tie up IIS when they're running. I'm interested in what would be happening in IIS under the following scenarios:

* Simply running the task within the postback request - would this tie up IIS thread(s) for the time the process is running? (btw, I'm not intending to it this way but interested all the same)
* Starting the task on another thread and therefore completing the postback request. Feedback would be provided via some kind of broker object in between the task and asp.net. Would the task's thread live within IIS/use up IIS threads?
* Similar to previous except using MSMQ, this seems like the best solution but I'd prefer option 2 to begin with.

I've tried using performance monitor to track threads/processer time/context switches but it's tricky to see what affect long running processes are having on IIS.

Thanks in advance!