In your shoes, I would tend to lean towards getting a Dell desktop. While laptops are more versatile as far as mobility is concerned, they aren't nearly as "modular" and as a result the hardware is a bit more difficult to upgrade down the road (if you should want to add more memory, a Blu-ray drive, etc.).
Since it sounds like you want a high-end machine, the Dell XPS 710 series would probably suit your needs quite well. A great computer, good warranty, excellent customer service, etc. As always, lots of customization options at your disposal.
Last but not least, if you are getting a high-end machine anyway I would go with Vista Ultimate version instead of Home Premium. Here is a comprehensive breakdown of the different versions to help you decide...
http://www.winsupersite.com/reviews/winvista_02.asp