Until a few months ago, I worked fulltime in a computer-store where every day an average of 10 laptops were sold.
9 out of 10 laptops came with Vista, usually the older types or Business models had XP professional installed.
What I suggest really depends on your own computer-skills.
Personally I find Windows Vista 'better looking' then Windows XP, but that's about it.
Microsoft has always claimed that they wanted to make their OS as user-friendly as possible, but they have seriously failed to do so with Vista.
Many of my customers (I do computer-repairing atm, self employed) struggle to adjust settings in Windows Vista, where they could easily make their settings in Windows XP.
Not only the interface got worse, also the performance.
For Windows XP, you didn't require to have a fast computer.
Even on a good old PIII, XP and XP Pro could work smooth as long you provided your computer with enough memory, but in Vista, your computer needs to have a minimum of 1gb memory installed in order to keep things going.
Lesser memory will seriously slow down your system when doing multiple tasks (even with Dual-core CPU)
Personally I recommend 2 GB to be in order with the most common tasks.
Vista had a huge amount of errors when it was launched, but that goes for every OS Microsoft makes.
Microsoft works the other way around you know.. First they make a product and then they start to fix it.
When XP was launched, I remember half the globe praising Windows 2000 or even 98 as the best OS atm. XP should be banished for it's errors, but in less then a year, most errors were removed and not long after that the world praised Windows XP.
So I think it'll be just the same with Vista.
Also, check google for 'XP Themes for Vista'.
There are many Themes which make your interface look identical to Vista. I really prefere those for when it comes to changing backgrounds, themes, colours, screen-settings and so on.
About laptop-brand, I recommand the Sony Vaio.
I worked with this machine for several months (both XP and Vista on it) and I wouldn't want any other laptop anymore.
I tried Acer, HP, Toshiba, Sony, Dell and probably some others I can't come up with, but nothing beats the Sony Vaio.
Sony Vaio gave the best performances in both graphical games, speed and I really liked their screens.
This is mostly because Sony uses different lamps in their laptop-screens. Most manufacturers use 1 lamp, Sony often 2, depending from model to model.
Downside is that Sony Vaio isn't as cheap as the average HP Notebook.
HP is ok though.. they do have a very nice service and a 30 days DOA warranty (Dead On Arrival), meaning that if there is a problem within the first 30 days, you can just trade it for another one straight away. (At least most of our shops here give that warranty), and then ofcourse the 2 year warranty (3-4 weeks repairing usually)
Acer: BIG NO.
Anyway, I just noticed that I'm typing a bit too much, which I usually do when it comes to computers
Not sure if you have any use of it, most of the things I mentioned comes from both personal and professional experience, therefor not the right thing though :p