For those looking to buy a new pc, it may be worth holding on until after the 1st of July. Looks like Microsoft will release Windows 7 as a free upgrade!
Quote from: Windows7News.com
Will Microsoft provide upgrade opportunities?Microsoft will provide upgrade opportunities both for Windows XP and Windows Vista users. Free upgrades are provided for users who purchase a computer system with Windows Vista after July 1, 2009. Not all versions are however eligible for the upgrade. Upgrades are only available for systems of the same language and the only allowed upgrade paths are
Windows Vista Home Premium -> Windows 7 Home Premium
Windows Vista Business -> Windows 7 Professional
Windows Vista Ultimate -> Windows 7 Ultimate
There will be no free upgrade for all other versions of Windows Vista that are purchased after July 1.
http://windows7news.com/2009/04/28/windows-7-everything-you-need-to-know/