In Windows XP Professional Edition's, go to Start and then Run.
Type gpedit.msc and press Enter.
In the left pane, select User Configuration > Administrative Templates >
Windows Components > Windows Explorer.
Double-click Maximum number of recent documents in the right pane and select
Enabled under the Setting tab.
Increase the maximum number of recent documents to a number above 15.
The menu will show only the 10 most recent files of any file type--for
example, 10 .xls (Excel) files, 10 .doc (Word) files, etc...