To be clear, developers must install the Platform SDK 6.1 which is
part of  "Windows SDK for Windows Server 2008 and .NET Framework 3.5"
and is available at the following link (repeated from above):
http://www.microsoft.com/downloads/details.aspx?FamilyID=e6e1c3df-a74...

This installer contains lots of stuff including VC++ 9.0 (which we
don't use), so do not install it unless you know how to keep VC++ 8.0
(which we use) and make sure that it stays as the compiler for
Chromium builds.

When the installer completes you must use the "Windows SDK
Configuration Tool" in the Start menu, under Microsoft Platform SDK,
to enable this as the current SDK. Otherwise Chromium builds won't
pick it up.

After it is installed and configured you must "clobber" your build
which means to recursively delete (rd /s /q) the src\Chrome\Debug and
src\Chrome\Release directories
under your SVN client. A "gclient sync" is also required. You can do
the clobbering and SDK install in any order but the build must be done
as the LAST step.

- Itai