I absolutely love the Windows task manager almost as much as I love TOP on ‘Nix systems. I use my task manager to monitor network activity of a particular box by clicking on the network tab and seeing throughput. I use the process section to see what is running on my computer (and I can kill processes by right clicking on them and ending them or their entire process tree.) I can also kill applications by using the application tab with the end task button.
Make the task manager your friend! You never know when you are going to need it next!