Update README.md

Author: joeferner

README.md

@@ -14,6 +14,7 @@ $ npm install java
 * [Install node.js from source](https://github.com/joyent/node/wiki/Installation) (using: vcbuild.bat release)
 * The directory where jvm.dll exists must be in the PATH. (e.g. C:\Program Files (x86)\Java\jdk1.6.0_18\jre\bin\client)
 * Open a Visual Studio command prompt.
+* Your Java must be the same architecture as node. By default on windows this is 32-bit.
 
 ```bash
 $ set PATH=%PATH%;C:\Program Files (x86)\Java\jdk1.6.0_18\jre\bin\client