If you have a 32-bit implementation of MOSS 2007, you can’t perform an in-place upgrade to SharePoint 2010. Microsoft recommend 1st upgrading from MOSS 2007 32-bit to MOSS 2007 64-bit and then upgrade to SharePoint 2010.

With this best practice, we will be able to identify what assemblies, WebParts, iFilters, 3rd party controls, etc. not supported in 64-bit environment and we can recompile them.

Get ready for SharePoint 2010 upgrade: http://go.microsoft.com/fwlink/?LinkId=155576

If your existing SharePoint environment on Windows Server 2003 and in 32-bit, Microsoft recommend upgrading from 32-bit to 64-bit and also from Server 2003 to Server 2008 at the same time and then upgrade from MOSS 2007 to SharePoint 2010 as a separate exercise.

With regard to Database server, if you are using SQL Server 2000 in a 32-bit mode, upgrade it to 64-bit SQL Server 2005 SP2 or SQL Server 2008 at the same time and then upgrade it to SharePoint 2010 as a separate exercise.

Don’t mix up architecture upgrade (32-bit to 64-bit), underline product upgrade (Server 2003 t0 2008 & SQL Server 2000 to 2005/ 2008) and SharePoint upgrade since we will not be able to isolate any issues arises.