In tip 10436 » How can I run a Storage Report in Windows Server 2003 R2?, I reported that Storage Reports at stored at %systemdrive%\storagereports\interactive by default.
To alter the default location:
1. Start / All Programs / Administrative Tools / File Server Resource Manager.
2. Right-click File Server Resource Manager (Local) and press Configure Options.
3. Select the Report Locations tab.
4. Type a new default folder for the Incident report folder, Scheduled report folder, and the On-demand report folder.
5. Press OK.