After spending a few hours downloading and installing all the prereqs on Windows XP (Cygwin, Visual Studio .NET 2003) to build the OpenJDK, I got to the point to discover that the OpenJDK will currently not build on Windows, because there are files missing in the binary ‘plug’.
The OpenJDK comes in a couple of different downloads, one of the files being the ‘binary plug’ – this contains platform specific binary code that is currently not available for licensing reasons to be part of the open source OpenJDK, and so is provided ‘as is’, as the original binary files that are shipped with current JDKs. Unfortunately, since there is no mention of this on the project website (the Windows binary plug download leads you to believe that it is complete and all you need to be able to build on Windows) until you get to this step in the build process, you find out that there is one file missing in the binary files, t2k.lib, and without this you cannot build on Windows.
This missing file is described in this bug logged on the Sun site.
Apparently you can build on other platforms, Linux, Mac OS X, so I’ll investigating the Linux build instead for the time being until this issue is resolved.