SharePoint Server 2010 Preliminary System Requirements
1.SharePoint Server 2010 will be 64-bit only.
2.SharePoint Server 2010 will require 64-bit Windows Server 2008 or 64-bit Windows Server 2008 R2.
3.SharePoint Server 2010 will require 64-bit SQL Server 2008 or 64-bit SQL Server 2005.
Microsoft also announced some important requirements regarding SharePoint Server 2010 browser compatibility:
-To ensure the best possible experience across multiple browsers, Microsoft is focusing on SharePoint 2010 engineering efforts on targeting standards based browsers (XHTML 1.0 compliant) including Internet Explorer 7, Internet Explorer 8 and Firefox 3.x. running on Windows Operating Systems.
-In addition, Microsoft also planning to increased level of compatibility with Firefox 3.x and Safari 3.x on non-Windows Operating Systems.
-Due to this focus Internet Explorer 6 will not be a supported browser for SharePoint Server 2010.
You can find additional information on Microsoft’s Support Lifecycle Policy including specific dates, product information and support offerings here: http://support.microsoft.com/gp/lifepolicy.
Advantages of 64-bit hardware and software (Office SharePoint Server 2007)
http://technet.microsoft.com/en-us/library/dd630764.aspx
Migrate an existing server farm to a 64-bit environment (Office SharePoint Server 2007)
http://technet.microsoft.com/en-us/library/dd622865.aspx