I've got a Vista Ultimate laptop (HP 17"), and one of the new Mac laptops (13.3"). They're both good, and I use them for different purposes. BTW, I'm a software developer, so my needs are different from yours.
Both platforms will readily do what you've described. The Mac really is impressive. Apple has really mastered the "wow" factor, but Vista (with a little bit of Stardock thrown in for good measure) is nothing to sneeze at. There's really nothing to be afraid of here.
I tend towards the "power user" end of the scale, so I'm usually looking for a higher-end unit, but unless you under config your system, you will be happy with either system.
In my case, I wanted the 17" screen to watch video on, and the 13.3" screen for when I am on the road. For development work, I have a 22" widescreen that I can add as a second monitor to either of the systems. I doubt that I could use the 12" screen that you currently have for regular work. Not to brag, but I rarely work with only one monitor unless I am on the road.
If you're the type of person who needs help, then I'd go with the kind of system that your friends/family have. If not, then either go with your heart wants or your budget can afford.
Good luck!