Now what should you do if you have a slower computer? Well XP is still available to the consumer, but not for much longer, M$ (Microsoft) has already pulled the plug on mainstream support. There will still be security updates for awhile, till 2014. But in case you can't find a driver or something worse, like a bug pops up, you won't be able to get help from the people that made the software.
I must also talk about Vista, even though I strongly believe it shouldn't have been released, it sucks as an operating system. It's slow, RAM hungry, incompatible with most older hardware, full of bugs, and comes standard on any new computer.
Most new computer warranties specify that you can't change the OS or it will void the warranty. WHY?!?!?!? That's like buying a new car and not being allowed to change the color, or add new seat covers, etc... Why are companies doing this to consumers?
Anyway, my original point is that even if computers come with Windows 7 on every new computer, I don't foresee many people complaining about it, because it just WORKS! M$ says that they built it on the old Vista platform, I think they didn't finish Vista but rolled it out anyway to make some money to finish making 7. (or to pay the investors some cash too)
So in conclusion, I believe if your computer can handle it, get Windows 7. Even buy it when it comes out in the retail stores. I'm sure you'll love it!