[AccessD] A Question of MSExpress and MS SQL

I must admit that I currently have done no research on the subject but the
night is still young.

I tried the simple way of 'attaching' an mdf and ldf files, created in MS
SQL Express to my MS SQL 2000 sever but the process crashed saying something
like 'Could not find row in sysindexes for database ID 10, object ID 1, Run
DBCC Checktable on sysindexes....' 

I was wondering if it does not work because SQL Express is of a much newer
format than SQL 2000 or is it because they are like apples and oranges and
'Express' will never be compatible with any version of 'MS SQL'?

What would be the easiest way to transfer structure and data across?

TIA
Jim