The long anticipated release of SharePoint 2010 is almost here now! Arpan Shah, director of SharePoint, announced the official date of launch to be May 12th. The RTM is going to be even earlier, April, so you should be able to download the bits directly from MSDN or TechNet at that time.
At the same time, SharePoint Designer 2010 should become available as a free download from Microsoft’s site. My advice would be to download it right away to truly start taking advantage of the 2010 release. Please keep in mind that SharePoint Designer 2010 will not work without SharePoint 2010 so you cannot use it to attach to a SharePoint 2007 site.