W7 is Vista underneath the interface but, unlike Vista, actually works as it should. I have been using the Release Candidate (the beta W7) for many months and it is solid, fast and reliable. I do even know of a large company of scientists in the USA who are running their entire office on the RC version!
The reasons it works so well can be explained but would take some time to do so. It is a disgrace that MS released Vista at all. Apart from Windows ME, Vista has to be the worst offering from MS ever.
I would have no hesitation in buying a laptop with it included and have even bought 3 copies via the pre-ordering scheme (excellent value at the beginning) to load on to my PCs.