I had the same problem with french products. No matter what they are - games, software - they all are in french. I don't know how much this will help, but with my HP laptop I received this CD: "hp notebook Language Pack Recovery CD - contains multilingual user interface for system restore / WinXP Pro (includes over 10 languages)". With this CD I can change the interface language. Maybe you have something similar, or you can download something similar from the producer's website.

Of course, there's always the possibility to install an english version of Vista...