Never had the pleasure to play the XboX version myself, but for the PC version the default start is that:

-The cursed princess died, therefore Temeria is left without a legitimate heir (small difference, if she survived she'd be married off to a foreign monarch, so the king's bastard would still be of vital importance, as the throne is in danger of being inherited by a foreigner).
-Geralt fell in love with Triss Merigold (again, should you have chosen the other girl, you'd part ways anyhow, and the Triss-Yeneffer-Geralt triangle means you can get as close or as distant from Triss as you wish).
-Geralt is not at best terms with the Order of the Flaming Rose (which plays a minor role in the last chapter).
-You start with less money and without the transferable swords or Raven Armour (but you'll soon find/cfart better gear anyhow).

As far as I remember other TW1 choices are irrelevant to TW2, but I might've missed some.