You should install SQL 2008 workstation compponents. They will be installed side by side with SQL 2005 workstation compponents. The SQL Native client 2008 will be installed as a part of it. It'll give your applications access to all the new SQL 2008 features.

>I can connect on the box it is installed on but I only have SSMS 2005 on the original box. If I install SSMS 2008 on the original box, will I still be able to connect to the earlier versions on this box? Will that install some form of connectivity software that will open up the access?