Performance Monitor (perfmom) creates log files using the Binary Performance Log (BLG) file format. Since these files are binary in nature, they can't be directly imported into databases such as those used by SQL Server or into Excel spreadsheets.
However, you can use the Relog command-line tool to convert BLG files to CSV format which can then easily be imported into SQL databases or Excel spreadsheets.
The syntax for the Relog tool can be found at http://technet.microsoft.com/en-us/library/cc771669(WS.10).aspx
Mitch Tulloch is a Microsoft Most Valuable Professional (MVP) and widely recognized expert on Windows administration, deployment and virtualization. For more tips by Mitch you can follow him on Twitter or friend him on Facebook.