to be going beta crazy for Windows at the moment with its small scale beta releases of Service Pack 3 for Windows XP and Service Pack 1 for Vista. While rumors persist that both betas have already been leaked to the Internet, it is obvious that Microsoft is accelerating the process of getting both of these Service Packs out the door.
As for Service Pack 3 for Windows XP, this is the first that we have heard about it since Microsoft announced some time ago that it was in the pipeline. What we know at this time is that it is said to contain fixes for over 900 reported problems.
Many of these 900 fixes, however, have been resolved in post SP2 hotfixes and such, so it isn’t all “new.” The new Service Pack is said to weigh in at around 350MB. As for new features, we have not heard any whispers of anything new to be included with Service Pack 3, but that could change as we get closer to its release.
The Vista Service Pack 1 really does not get much of an update other than the current build of SP1 for Vista is being delivered as an ISO at the moment, as Microsoft has not delivered an actual update package yet. We can only assume that this is perhaps to make it larger and more difficult to download and distribute, should it be leaked.
New indications seem to suggest that Microsoft might choose to distribute both Service Packs at one time, rather than pushing them out the door individually. We have no clue what would be gained by releasing both Service Packs at the same time. Right now we can only speculate, but it seems that the Service Packs are at least on course for a first quarter 08 release, unless Microsoft is able to push it out the door late this year.
The best source for more info is here