Upgraded from SQL Server Express to standard but CPU usage is maximum 50% on dual core
If you want to see pain points of a query capture the actual execution plan via SSMS when you run it. Viewing this within SQLSentry Plan Explorer (free!!) is a bit more easy on the eyes than what SSMS will show. There are some good blog post and articles scattered around the Internet on how to read an execution plan if you need it.

Capture Actual Execution Plan: