some companies have such terms abt os and its always mention in terms and condition. though never experienced with dell hp sony till date but its better to confirm with lenovo
Its got a ~250GB partition (c: ) with windows and a 30GB partition (D: ). I wanted to install windows in the 30gig and keep 250 for data. and load windows 7 ultimate
^boot from the win 7 dvd and at the drive selection page, delete all the partitions and create as many you want of your preferred size, before that just backup your data