As the others have said, you may not be able to use some of the DMVs. I also have just migrated a lot of 2000 databases to 2008 and have left many of them in 80 compatibility mode. The applications continue to function as they did prior to the migration and I gain some of the benefits of SQL 2008 (like compression).
Jason...AKA CirqueDeSQLeil
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I have given a name to my pain...MCM SQL Server, MVP
SQL RNNR
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