Installed the RTM of Windows 7 on my home PC a couple of days ago. Then I tried installing SQL Server 2008 on it. Found out that SQL Server 2008 is incompatible with Windows 7. To make it compatible you would need to install SQLServer Service Pack 1 or later.
On the same note, to make SQL Server 2005 compatible; you would need to install Service Pack 3 or later.