Microsoft listed all fixes on their website which are included in Windows XP Service Pack 2.
This article lists the problems that are fixed in Microsoft Windows XP Service Pack 2 (SP2). Service packs are cumulative. This means that the problems that are fixed in a service pack are also fixed in later service packs. For example, Windows XP SP2 contains all the fixes that are included in Windows XP Service Pack 1 (SP1). You do not have to install an earlier service pack before you install Windows XP SP2.
The list can be found here. Don't be surprised, it's a huge list.