Vista Home Premium came preinstalled on the laptop I bought in August. I have to say I haven't had any problems with Vista in these seven months. For that matter, I've never had serious problems with any version of Windows. I've never had a virus or malware infestation. My systems do not slow down the longer I use them. I do run a tight ship.
I haven't installed Service Pack 1 yet. I generally wait at least a month on things like service packs so the dust can settle. You can find out whether there are problems showing up frequently and make a more informed decision. But even if I wanted to install SP1 now, Windows Update isn't offering it to me. In reading up on this in the Microsoft Knowledge Base, I discovered my sound driver is one of the rather common ones that don't interact well with SP 1, so SP 1 won't be offered to me until I upgrade the driver or Microsoft issues a fix. There are some pretty common audio drivers that prevent SP 1 from being offered through Windows Update: AC97 and two Sigmatels, among others. Mine is one of the Sigmatels. It's a Gateway laptop, so I went to their support site and looked for a newer driver. Nothing. Nor was there one word about SP 1. So I guess I'll be waiting for Gateway and/or Microsoft to get their act together.
I use VL 5.9 Deluxe about 80% of the time on that computer, maybe 90% of the time. I don't dislike Windows, I just like Linux much better.
As for problems with SP 1, every service pack for Windows that I can remember has caused problems for some systems. In the vast majority of cases, they work. But if you're one of the minority who winds up with a mess, that's not any comfort. The SP has an uninstall option but that doesn't always work. Best advice: make an image file before you do anything major that affects the system.