One of the most frequent questions I am asked is "what computer should I buy and when should I buy it"? The first part of that question depends on the individual and I ask a lot of questions before I attempt to give an answer BUT the second part of the question is usually easy; the answer I usually give is "as soon as you want to". Right now that could be the wrong answer.
Microsoft is preparing (mind you this was originally due in 2004) to deliver it's next operating system , Windows Vista, in January of 2007. Recommended (by Microsoft) hardware configurations for the new operating system are considerably greater than they are for WindowsXP.
For Windows XP recommendations see here.
For Windows Vista recommendations here.
If you look at the Vista recommendations link above you will see that Microsoft uses two distinctly different terms to identify computers that will run this new operating system. The term "Capable" describes computers that "will deliver core experiences.... at a minimum". For this you should read "it will at least boot up but may or may not be capable of running the programs you need to run". The term "Premium Ready" is used to describe a computer that will not only run your applications but will take advantage of the new aspects of the operating system, especially the new user interface.
As of 9/13/2006 Dell Computer's website does not seem to offer any systems that are identified as "Vista Premium" compatible and their use of the words "Vista Capable" is very confusing. For someone unaware of the distinctly different meanings of the terms "Capable" and "Premium" in this context, much of the text on the Dell web site does not make the difference clear. HP's web site does a much better job of describing the difference.
Bottom line, at present it is not clear that all manufacturers (and in particular all retail sales clerks) will give you a clear idea of what if any part of the new operating system will run on a given system. I also believe that as we start getting closer to the holiday gift giving season, we will see major computer manufacturers and retailers selling systems bundled with a free upgrade to Vista when it is finally brought to market by Microsoft.
All in all, this is one of the few times that I am advising folks to wait a few months before making a new PC (desktop or laptop) purchase. Let the dust clear a bit first.