Microsoft provides pages of documentation that indicates what has changed in XP SP2. There are many file changes of course. Please visit the site Windows XP SP 2 for IT Professionals for links to articles that will provide this information for you.
Some people report no problems with AOL after upgrading to SP2, while others complain about problems playing AOL games. The problem may be that the games need to connect to the Windows XP computer, and the Windows firewall is blocking that access (the Windows firewall is turned on by default after the installation of SP2. Blocking access to your computer from the Internet is a good thing; it may protect you from attack). You may be able to correct this situation by a number of different methods. First, when attempting to run the game, if a security alert informs you that the program is attempting to access your computer, you can click on "unblock this program." Second, you can configure the firewall to allow the program to access your computer. Explicit instructions can be found in the Microsoft knowledgebase article 842242.
Please do NOT disable the firewall, and please do NOT get in the habit of clicking "unblock this program." Otherwise, you may allow an intruder to attack and even gain control of your machine. An attacker might then add a virus or worm, use your computer to send out spam or steal private data from your computer such as any credit card numbers or other data you may have there.
This was first published in September 2004