Dear xxx, Good morning/Good afternoon. 你看领导知道你是谁吗?知道的话,就直接入主题就好了。不知道的话,自我介绍一下。This is XXX from XXX dept. Glad to contact you here. For convenient working, I would like to apply for installing WIN7 systerm. As per IT dept's requirement, I need to get your kind approval. May I have your permission here? Thanks a lot. Thanks and best regards,xxx