Contributed By: Cliff Hobbs [MVP SMS]
In SMS 2003 SP3 the supported Client Platforms are as follows:

Advanced Client

• The minimum supported Client OSs are now either Windows 2000 SP4 or Windows XP SP2. Earlier versions are no longer supported.
  
  NOTE: If you upgrade an SMS Site to SP3 that contains Clients with OSs no longer supported by SP3, such Clients will NOT receive any hotfixes.  Any SMS 2.0 Clients in a Site upgraded to SP3 will be unable to report their Software Inventory.  Microsoft's recommendation to address both these issues is to upgrade such Clients to an OS supported by SP3 first and then install the SP3 Advanced Client.
  
  
• The SP3 Advanced Client can be installed on a Windows Vista machine (SP3 is the first SMS version to provide full Vista support).
  
  
• 64-bit server platforms are supported by the Advanced Client.

Legacy Client

• The Legacy Client cannot be installed on any machines running Windows 2000 or later. If you have any Clients like this you'll need to upgrade them to Advanced Clients when you upgrade their assigned Site to SP3 as failing to do so will prevent them from receiving hotfixes.  Microsoft's recommendation is to upgrade such Clients to the Advanced Client before upgrading their assigned Site to SP3.

To see other SMS Design related FAQs click here.