Hi, you have to consider a SQL upgrade and LANDesk database upgrade.
Generally it could be enough to make a LD9.0 database backup on file.BAK from SQL2005 management tools and restore on a SQL2008; so you have now a LDM9.0 SQL2008 db.
If are not upgrading but just moving database then you have to tell LDMS console (Configure --> Sevices panel) which is the new database server (Istance,database,User,password).
If you are upgrading from LDMS9.0 to LDMS9.5 you will ask to set LDMS9.0 database source information (the moved one in SQL2008) during installation of LDMS9.5 and CoreDButil.exe process wil upgrade database from LANDesk point of view.
Read this docfor upgarding http://community.landesk.com/support/docs/DOC-26992
Regards