Going to 2008 Server Std from SBS2003. How restore secure channel?

We want to implement a 2008 server to replace a 2003 SBS. Looking at various postings online, it looked like we could install the 08 server and promo it and when ready, take down the old SBS server and then seize the operations masters roles on the new server. I started this process, and got as far as the new machine is a DC. It has, however ceased to communicate properly with the older server. The secure channel needs reset, but I tried that and it denied me access. Now DNS info won’t even load – it seems to be cut off from AD. ?