DExposE2 is a program for vista to provide the Expose function.
Comparison:
Mac OSX:
DExposE2
Although DExposE2 is quite lag-free and resembles Mac OSX's Expose quite a lot, it has a horrendously imba memory leak. After launching the program for a mere 3 hours, its RAM usage skyrockets to 900+MB. Before that, I left my comp on for like 12 hours and it finished up every single MB of ram available, making the computer very lag and cannot open any process.

Luckily I have found alternatives to DExposE2. Try Switcher @ http://insentient.net/. Its interface is more streamlined and more user-friendly and more appealing. I don't suppose it would have memory leaks as I have just used it for like 10 minutes. Try it out =D