For those who, like me, are behind a corporate web proxy, setting up node and using npm can be a real pain.
Open a Command Prompt Window (`start` -> `run` -> type `cmd`)
1. C:\> cd C:\Users\youruserName
2. C:\Users\youruserName> npm config set proxy http://proxy.server.net:80
3. C:\Users\youruserName> npm config set https-proxy http://proxy.server.net:80
or http://domainusername:password@proxy.server.net:80
4. Open C:\Users\youruserName.npmrc to verify config items.
Voila! Install an npm package...
C:\Users\youruserName> npm install bower -g