XP SP3 and IE
I found this blog post rather interesting today. It's an explanation of how SP3 and IE will work together. Essentially it comes down to the following:
If you have IE6: It's business as usual... you will be offered SP3 via Windows Update and you'll still be running IE6 after the update.
If you have IE7: You will be offered SP3 via Windows Update, however once you complete the install of SP3 you'll be unable to revert to IE6. Due to updates that are included for IE6 (which won't be installed since you have IE7), IE7 cannot be uninstalled.
If you have IE8 Beta: You will NOT be offered SP3 via Windows Update. As well, once you install SP3 you will NOT be able to uninstall IE8 Beta. Microsoft is recommending that you uninstall IE8 Beta, install SP3 and then reinstall IE8 Beta if you are using it.