I don't know what the Plesky software is, so I can't help there.

If you can't run performance monitor on the server, but you are still interested in getting some of the counters available from there, you can use dynamic management objects (DMO) to access this. For example, to see the workers connected to and operating in the OS, you can use sys.dm_os_workers. To see activity directly against the SQL instance, you can use sys.dm_exec_requests, which will show currently executing procedures. To check on statistics on tables, etc. you can use sys.dm_db_index_physical_stats.

There are a whole ton of ways you can check on the system using DMOs. There's a great new book, focused on performance tuning with them called "Performance Tuning with SQL Server Dynamic Management Views" by Louis Davidson & Tim Ford. I highly recommend it.