Restoring to factory settings means just that .HP and PB are basically the same. Yo will have whatever OS your computer came with. If you upgraded from XP Pro to win 7 It will have the original OS system Not what you upgraded to.
Same as your programs you added and any saved data Inc Mail unless you saved these elsewhere they will be wiped as returning to original settins will normally Format the System So if you saved an image from when it was running restore from that image.
Clearly more information is required Such as did you save and Image if so using what program, and to where such as DVD or external Drive