Amazingly, even in SQL 2008 there's no performance testing/tuning GUI. But of course, you just need to know where to look to find free tools. Welcome to Codeplex.
SQL Nexus takes advantage of the SQLDiag command line tool that ships with SQL Server, sucking in DMV and Trace data to present in a great drill-through Reporting Services based interface.
Within an hour, I'd identified 2 hardware based issues with solid evidence to present to management.
Tip: Read the installation steps carefully; it's not an all-in-one install. Also, when directed towards a download of PerfStatsScript.zip, look here for the download.