From what i read you won't be able to use icloud on windows xp, have to use windows vista or 7 in order to install icloud. iphone 3 gs should work with icloud but again will not be able to get full benefits from it until you upgrade to win 7 on your computer or have a mac.. There are a vast number of mobileme users who now cannot migrate to ios 5 and the icloud service because they are using windows xp. please apple, consider writing a windows xp icloud control panel.. For windows xp users, here is a way to install the icloud control panel applet…it seems to work fine (for now) i managed to install the control panel on xp…seems to work great..
