Do the first step Veg suggested and alternatively you can download this;
http://www.microsoft.com/globaldev/tools/apploc.mspx - This will allow you to individually run programs in other language without converting the entire Window Operating system to another language, which can cause problem later on if you're installing programs in the future and forgot to switch back to english. Like installing programs that are suppose to be in english... but you get a japanese installation wizard guide instead...