is sccm client backwards compatible with sms 2003

For those of you wondering, the sccm client is not backwards compatible with sms 2003.  However, the sms 2003 client is backwards compatible with a SCCM environment.  Basic rule of thumb regarding SMS/SCCM is that the highest version must be at the top of the hierarchy.  So if your upgrading, you must either upgrade your central site first, or build a new SCCM site and point your sms central site to the SCCM site as its parent.  Then you work your way down the hierarchy upgrading Parent servers, then child servers, and secondary servers.  Never upgrade a server unless the server above it is already upgraded.  Once you've upgraded your entire environment, figure out how clients are going to determine their management server.  After you've put this in place the last thing to upgrade is the client.