"Hot Corners" is called Expose in Mac OS X. If you'd like to use it on Windows, there are a few programs available that will perform the function(s) you wish to use and possibly more. Here are some links.
Switcher: Switcher for Windows Vista
DExpose2: home (devrexster)
From what I've heard and read, Switcher is the best choice, although DExpose2 may be smoother in the transitions. I'd try them all and pick the one you like most.