Here's a useful query for showing how much processor a given database is consuming compared to other DBs. The query returns a perctentage. Note, this is a percentage of the overall processor usage of MSSQL. If MSSQL is using 10% of your server proc usage and a given DB is using 50%, you should realize that the DB is, in reality, using 5% of the capacity - no cause for alarm. If, however, a SQL server is at or near capacity (70% or above) and a given DB is using the majority of the proc cycles, then of course, that DB is a good candidate for upgrading to a dedicated server (or at least one with more horsepower). Of cours, this assumes that you have examined the schema, indexing and caching to insure it scalable to begin with.
"Sysprocesses is stored only in the master DB." I accidentally deleted the note (sorry Phil). So the revised query should have a "use Master" command at the top. It goes without saying that you have to have sa permissions to get server level stats.