I see no reason to convince anyone to do anything, but I can go ahead and list a few of the things that make Vista appealing to me as a user.
System-wide indexed search: Functionality-wise, I think this is somewhere near the top of the list for me. Many of you here know that I'm a fan of Windows Desktop Search even on XP. It's great, but it still feels like an add-on. On the other hand, indexed search is at the core of Vista; it's pretty much present everywhere, and I think power-users will find it useful. And before anyone brings it up, indexed search is *NOT* a substitute for a disorganized file/folder structure; it just makes things, especially repetitive tasks, a whole lot quicker in my experience.
Previous Versions: The ability to undelete files or restore previous versions of files. I think this is a nice safety net to have. A few months ago, I accidentally pulled the power cord and turned my desktop off. F@H was in the middle of writing checkpoint data to the disk, so when the system came back up, the data was in an inconsistent state. I used Previous Versions to recover the most recent well-formed file, and the process resumed from there without a problem. Yes, it's a trivial example, but that could have been more critical data. Not a substitute for backups, but it's faster and more convenient to recover from such problems this way.
Much better out-of-the-box hardware support: XP is five years old now. That's old. It predates most of the hardware in our PCs. Everytime I reinstall XP on a machine for some reason, it's the same tedious, time-consuming process of going to every hardware vendor's site and downloading the drivers for everything. I've installed Vista on three different machines with vastly different hardware, and almost everything was detected and worked out-of-the-box. It's a much more pleasant experience right from the start.
Tablet and Media Center enhancements: I have a Tablet PC. I also have a Xbox 360. They're both awesome devices. In order to stream video to the 360, I need MCE 2005. MCE 2005 is a separate SKU without Tablet support, so I have to choose one or the other. With the Premium Vista SKUs, I get both Tablet support and Media Center. And they both include evolutionary enhancements to their XP-based predecessors - Vista automatically learns as you write on a Tablet, improving handwriting recognition, for example.
Fit-and-finish: Not the most important thing in the world, but I like my environment to look nice and consistent. Aero is certainly not perfect, but it's a big step up from XP's UI, even with third-party themes, in my opinion. This is totally subjective, I understand, and some of you might prefer XP. Up to you. Still, this isn't really a deal-breaker one way or another.
Other than that, I think it's just lots of small things everywhere that make using Vista more enjoyable for me. There are some things I like better in XP, but overall, I think the good in Vista outweighs the bad. Others might be able to list other Vista features that they find compelling, like BitLocker or UAC, for example, that you and I might not.
Again, I don't benefit in any way if the guy next to me switches to Vista, so I'm not trying to convince anyone or change their opinions, but since you asked, I just thought I'd tell you why I'm personally going to upgrade (besides the fact that I'll have at least three, if not more, free Ultimate Edition licenses to use anyway). I don't "need" it (and as Grandmaster said, nobody does), but I want it. 🙂