It is advisable to test the new OS in your Hardware before upgrading and then test the software you must absolutely keep running in order to decide whether to upgrade.
I believe that from a hardware standpoint this transition will be more seamless that the one form XP to Vista, because the code has not changed dramatically and after two years only stupid and miserable hardware vendors wont be able or willing to provide you with an updated driver.
If your printer does not work with Vista it isn’t Microsoft’s fault, it is your peripheral manufacturer who sees no profit in releasing that little piece of software and wants you to buy a new one.
What I would be worried about is software compatibility, specially if you are moving from XP to Windows se7en or even from 2K to seven.
Starting on July 1st OEM CAN (if they so choose) offer you a free upgrade to windows 7 (whenever it is released) if you comply with some conditions.
The Windows 7 Upgrade Program is designed to assist Microsoft’s OEM partners in minimizing the number of end users who may postpone acquiring a new computer because of the impending release of the Windows 7 operating system. This program allows OEMs to offer an upgrade to Windows 7 to end users who qualify.
This is a consumer-oriented program targeted at individual consumers and small businesses that have purchased eligible PCs during the Program Eligibility Period. End users will have to meet these requirements to be deemed eligible for the upgrade to Windows 7 when it is released :
* End users must purchase a new PC that is pre-installed with an eligible Windows Vista Operating System (OS), during the program eligibility window.
* The PC must have a valid Certificate of Authenticity (COA) attached.
* The only Windows Vista® versions eligible for the program are :
1. Windows Vista® Home Premium
2. Windows Vista® Business
3. Windows Vista® Ultimate
* Microsoft Windows Vista® Home Basic, Windows Vista® Starter Edition, and Windows® XP (all editions) are not qualifying products under the program.
* The Program does not support multiple upgrades for medium, large, or enterprise customers. Customers that want to upgrade multiple PCs should use the appropriate Microsoft Volume Licensing program. See http://www.microsoft.com/licensing for more details.
* The following are the only valid upgrade paths under the program :
1. Windows Vista® Home Premium -> Windows® 7 Home Premium
2. Windows Vista® Business -> Windows® 7 Professional
3. Windows Vista® Ultimate -> Windows® 7 Ultimate