PC Mag took a closer look at the Windows Vista Service Pack 1 beta:
Now, roughly nine months after Vista started hitting desktops, Service Pack 1 (SP1) has started its beta run. The latest iteration of the SP1 beta, which is closed to the public, reveals a useful set of OS updates, but one that's not as critical as SP2 was for XP. SP1 speeds up a few operations and enhances third-party program compatibility, but it changes little you'll notice in your day-to-day experience. Once again, the bulk of the development effort has gone toward upgrading security subsystems—elements that enterprise clients find appealing but consumers and small-business users won't really notice. Still, given that Vista is essentially a rewrite of XP meant to enhance security (and, of course, media features), I'm not surprised to see Microsoft take this route for the service pack..