C:Program FilesMicrosoft SDKsWindowsv6.0binildasm.exe
C:Program FilesMicrosoft SDKsWindowsv6.0Abinildasm.exe
C:Program FilesMicrosoft SDKsWindowsv7.0Abinildasm.exe
C:Program FilesMicrosoft SDKsWindowsv7.0Abinx64ildasm.exe
C:Program FilesMicrosoft SDKsWindowsv7.0AbinNETFX 4.0 Toolsildasm.exe
C:Program FilesMicrosoft SDKsWindowsv7.0AbinNETFX 4.0 Toolsx64ildasm.exe
C:Program Files (x86)Microsoft SDKsWindowsv7.0Abinildasm.exe
C:Program Files (x86)Microsoft SDKsWindowsv7.0Abinx64ildasm.exe
C:Program Files (x86)Microsoft SDKsWindowsv7.0AbinNETFX 4.0 Toolsildasm.exe
C:Program Files (x86)Microsoft SDKsWindowsv7.0AbinNETFX 4.0 Toolsx64ildasm.exe

What are all these different versions for? Which one should I use? Sumit Kumar is the Project Manager for “Windows SDK”, so I sat down with him to find out. Full details on my blog, http://blogs.msdn.com/lucian/archive/2008/11/15/where-are-the-sdk-tools-where-is-ildasm.aspx

(Note: the last four directories exist but don’t actually contain a copy of ildasm.exe. I just put them there for dramatic effect.)