Need help getting a higher screen resolution?

My friend has the same laptop model as me just newer. We have a Dell Precision m6300. he is running windows xp and have a nvidia quadro fx 1600m video card. i have the same except a 1500m card. Why can he only run a 1440x900 resolution yet i can go all the way up to 1900 x 1080 or 1900 x 1200. Why is this and how can he get it higher?