This week, Microsoft quietly issues early beta versions of Windows XP Service Pack 3 (SP3) and Windows Vista Service Pack 1 (SP1) to very small groups of external testers. Microsoft had previously said that it would ship a public beta version of Vista SP1 by the end of 2007.

Windows XP SP3, of course, is the more eagerly-awaited release. Microsoft last shipped an XP service pack, XP SP2, three full years ago and has since propped up the aging OS with hundreds of additional patches, making management of the system difficult and time consuming, especially for corporate customers. Unlike Vista SP1, however, XP SP3 is expected to include only bug and security fixes and no new features. XP SP3 is now due in the first half of 2008, Microsoft says.

Vista SP1, meanwhile, has become the subject of much speculation, despite including only minor new features that will benefit end users. Vista SP1 will include a kernel update, security changes, and an Instant Search makeover, but little else, according to the company. As with XP SP3, Microsoft plans to ship the final version of Vista SP1 in the first half of 2008.

One thing Vista SP1 won't do is provide a bump for enterprise deployments. Based on the data collected thus far, Vista deployments are mapping very closely to those of previous Windows releases in large companies, which tend to upgrade on their own schedules, and not those of Microsoft.