In the recent release of Windows 8 Consumer Preview, Microsoft made a huge change in their operating system, by completely removing the Windows Start button. as of yet, no registry setting has been discovered to find the lost start button, making the only option for consumers third party software.
This little piece of software is designed to be as small and simple as possible, but yet doing the best it can to mimic the start button. it's build, is a simple executable, which is simply "pinned" to the task bar like any other program. this gives it the advantage of easy installation. it doesn't require any changes to system files or registry setting, everything is done with a third party app. it comes in five different flavors, and it's distributed in both 32 and 64 Bit channels.
X64Start-Flag.exe - 64bit software
Simply download the zip, extract the contents to a folder where it won't get delete, then drag the executable to your taskbar to pin it into place. Upon first run you may get a security warning, just unchecked the box that says "show this warning every time" and click run.
It simulates a Windows key push, ie you get the same result if you push the windows key on you keyboard as when you launch this application. Remember to keep you hands of the keyboard when you push that button!