Scott Hanselman updates this list every year.  I use 4 of his top-10 utilities on my work laptop (my personal machine is a Macbook Pro).  I use TestDriven.NET a lot as well.  If you use Windows, the list is definitely worth a look.

A number of the applications Hanselman refers to can be found at Open Source Windows.  It’s all really good software  with an even better price ($0.00).