According to Microsoft:
Q. Can I install Outlook 2007 (or Office 2007) on the PCs in my Windows SBS 2003 network?
A. Yes. However, the Windows SBS 2003 client setup tools do not deploy Outlook 2007 to client computers. You must manually install Outlook 2007 on your client computers. For full compatibility, you also need to install some additional updates. For example, if you are running the Premium Edition of Windows SBS 2003, you need to install Service Pack 2 for Internet Security and Acceleration (ISA) 2004 Standard Edition, or else the e-mail will not get synchronized. For more information about the updates, see "Using Windows Vista and Outlook 2007 in a Windows Small Business Server 2003 Network" at the Microsoft Web Site.
Q. How do I keep my server that is running Windows SBS 2003 with SP1 or Windows SBS 2003 R2 compatible with Windows Vista and Office 2007?
A. You need an update for your server to ensure compatibility between Windows SBS 2003 with SP1 or Windows SBS 2003 R2 and Windows Vista and Office 2007. Microsoft Update will automatically install this update on your server starting in March 2007. If you need to update your network before then, install the updates described in the Knowledge Base article ?Update for Windows Small Business Server 2003: Windows Vista and Outlook 2007 compatibility (KB 926505)? at the Microsoft Web site.
Q. Can I add a PC running Windows Vista to my Windows SBS 2003 network?
A. Yes. You can add the Business, Ultimate, and Enterprise versions of Windows Vista (including 32-bit and 64-bit editions) to your Windows SBS 2003 network. However, you need to install the updates described in the ?Update for Windows Small Business Server 2003: Windows Vista and Outlook 2007 compatibility (KB 926505)? at the Microsoft Web site. Windows Vista Home editions are not supported in a Windows SBS 2003 network.
