you cannot see the memory and the cpu usage per database.
it's only per server (or per instance)
check the master..sysperfinfo table to see if there is something useful for you.
Or there is a tricky way to see the cumulated cpu and memory usage from the sysprocesses table.
To check the top 20 objects in the memory cache run the dbcc memusage command
Or you can run the profiler and check for the CPU and DatabaseId columns
Bye
Gabor