Sorry to hear that you're frustrated with Vista. I'm glad you're choosing to go with the MBP. I currently own a 17" version, and love it. Mainly because I have never had an issue in the year and a half since purchasing it, and because it replaced a bulky PC I built (and haven't turned on since I got my MBP).
I also have a Vista laptop, and although I only use it for watching streaming vids on Netflix and playing games, I haven't had any glitches so far. I don't use it for anything serious, which is likely why I haven't run into any issues. However, I use my MBP for everything serious, as well as creative exploration, and fun. I expect a lot out of it, and it's never let me down. I just feel that Apple computers are built for people like me, who have low frustration tolerance, and just want their expensive items to function properly, look nice, and have enough power to do whatever I want it to do.
The MBP has met my needs and then some. I don't have the latest, greatest model, and I don't resent the fact that since I made my purchase, there have been bumps in speed and capacity. I have maxed out my ram, and that wasn't really necessary, but it's just so cheap right now.
My point is, the likelihood that the new MBP's will grossly exceed what is available now is pretty slim. Think about the possibilities. These are the guesses I have as far as possible improvements. Note they are guesses, not reality. I think it's possible they may add a blu-ray drive. I think they will have the new penryn processors, and therefore a slight boost in speed without creating heat issues. They may add the multitouch trackpad. They may make the keyboard black and similar to the one in the MBA. Other than that, I can't really fathom any breakthroughs coming in the new model.
While all of my guesses may seem like a wonderful thing to wait for, the fact of the matter is this. The current MBP is a powerful, efficient, good looking machine. I have no doubts that you will be satisfied with it, and am also sure it will effectively perform any task you intend to throw at it. I'm assuming you are not planning on rendering a 3d movie with tons of effects in HD. If you are, then you should be looking at a MP, not a MBP. Fair assumption? Short of that, there is very little a MBP can't do, today.
I use my older model (C2D, 2.33ghz) MBP to create in Photoshop, Illustrator, Flash, Poser, Vue, Shake, Final Cut Pro, Dreamweaver, and Painter X. It functions perfectly, and I have no complaints. You are considering whether to get an even more powerful MBP (today's model), and therefore I'm sure you'll be pleased. Waiting for what may be even slightly more powerful is an option, but my point is, either way, you'll have a very nice machine. I honestly think you are facing a win/win situation here, and can't go wrong.
Having said that, good luck on your decision. I'm confident that either way, you'll be pleased.