OH! if it is just the last step causing a problem, try launching the “node.js command prompt” (it’s like cmd.exe but through node.js) and try the command from there. This worked for me like a charm.
Maybe I can put together a tutorial for this, but essentially you will want to make sure you have Windows SDK 7 (or 7.1) installed and then install the Microsoft visual C++ 2008 (and 2010) express redistributable. This will help node.js, node package manager (npm) and git chug along on Windows.