'..resgen.exe' failed to start... The system cannot find the file specified

Do you get an error with nant that looks like this:

[nant] C:\projects\...\Build-Scripts\......nant.build build
 Buildfile: file:///C:/projects/.../Build-Scripts/....nant.build
 Target framework: Microsoft .NET Framework 2.0
 Target(s) specified: build 


 build:
       
  [echo] Building '...': build.defines:'DEBUG;TRACE', dir.builddestination:'C:\projects\...\Source\build\...-debug-bin', build.debug:False
  [csc] Compiling 17 files to 'C:\projects\...\Source\build\...-debug-bin\....dll'.
  
  BUILD FAILED

        'C:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\bin\resgen.exe' failed to start.
  The system cannot find the file specified

I ran into this because I only installed VS2008 on this machine and a whacky VS2005 shell gets installed by SQL 2005 that has screwed up multiple tools, one of them is nant. To fix nant do the following:
Find NAnt.exe.config in the same directory as nant.exe. Find the element that begins

<framework 
 name="net-2.0"
 ... 

Within that element you'll find the following:

<project>
 <readregistry
  property="installRoot"
  key="SOFTWARE\Microsoft\.NETFramework\InstallRoot"
  hive="LocalMachine" />
 <readregistry
  property="sdkInstallRoot"
  key="SOFTWARE\Microsoft\.NETFramework\sdkInstallRootv2.0"
  hive="LocalMachine"
  failonerror="false" />
</project>

Note how it looks in the registry for sdkInstallRootv2.0. In my registry that was pointed to a VS2005 directory which doesn't actually have a full SDK. I pointed it to the new SDK paths Microsoft is using, in my case C:\Program Files\Microsoft SDKs\Windows\v6.0A\ , and then my project worked (well at least it got further than it did :) )

I hope this saves somebody some time!