Windows have launched Xp Service pack 3 and tested with the Vista ,although Xp Sp3 worked much better but that does not mean all... Recently i could not be able to install .Net Framework 2.0 on XP SP3.Beacuse Windows XP SP3 is not listed in the Microsoft .NET Framework 2.0 "system requirements" but why ? (maybe future release of Microsoft .NET Framework 2.0 will solve this problem). until now I was unable to use encarta on my Windows XP SP3 as well as Visual Studio 2005.
It is incorrect to say XP Service Pack 3 has been tested with Vista - it has nothing to do with Vista.
In fact it's incorrect to say that Microsoft have launched XP Service Pack 3 since it is not out yet, officially due "2Q 2008". They have (yesterday) made available on Microsoft Downloads a document (not really worth the paper it might be printed on) outlining what will be in XP Sp3 but that's all.