Yes, to be honest you probably will, but having said that, there are advantages to using Vista.
If you can get it free via a pre-install on a new laptop or desktop purchase (as I did), then you are laughing. I had to do this, because for one I needed a laptop, and secondly, since I teach people software applications, it would be kind of stupid if I had no experience with Vista. Also this is the only really sensible option if you are in Europe, as Vista is massively overpriced in comparison to its retail cost in the US.
Advantages are that you will be up to speed on the 'latest thang', and of course many new applications load and run very much better and quicker on Vista (FSX is a good example of this, where it is notably faster than on XP). It's pretty too, if that sort of thing floats your boat, personally I run XP and Vista in Classic mode so I couldn't give a toss about pretty window menus. Powerboost is one of Vista's best features however, and very cool if you are running short of RAM, so that might be a decider for you if you run HUGE files in stuff like Photoshop or 3DSMax.
Disadvantages, probably quite a bit of the software you already own won't like it. Vista also has totally paranoid default security settings too, which are frankly bloody annoying. Also note that Microsoft are already working on Vista's replacement and well along the way with it, so it's looking like like it won't have the longevity of XP, which given the mixed response that Vista has received, is probably going to be around for quite some time.
Virtually all MS operating systems are crap when released as you probably know, so things might change, but I wouldn't expect to see Vista as MS's flagship OS in five years time, that's my guess.
If you buy Vista to run on your current computer, you may possibly see a performance drop however, since the fact that they wanted to make Windows pretty like OSX, it's now more of a resource hog, so you can be just like a Mac owner now, with an overpriced and underpowered machine :rotfl:
Anyway, just a few heads up about what I've found, others might disagree with my assessment, so, in the end, I guess it's up to you.
Chock