If you’re a Windows 7 or Vista user, you may be frustrated with the number of recent items shown on the Start Menu. This is because Windows 7 and Vista use a different approach to displaying recent items. In Windows 7, the Recent Items screen shows only the most recent 10 items. This is because recent items are stored in a separate location on your hard drive than your previous versions of Windows. In Windows Vista, however, you can change how recently items are displayed by using the System Preferences window. To open System Preferences, click on the Start button and then click on System Preferences. In System Preferences, select the Display tab and then select Use Recent Items from the drop-down list. Now you can see all of your current windows’ recent items in one place!
What we are changing here is the amount of documents shown in this menu (I changed mine down to 1 for illustration)
Manual Registry Tweak
Open up regedit.exe through the start menu search box, and then navigate down to the following key, creating it if it doesn’t exist.
Add a new DWORD 32-bit value named MaxRecentDocs into the right-hand pane, and then double-click to open it up.
To set the value, you’ll first need to change Base to Decimal, and then you can enter any value you want. For instance, if you want to set it to 50, enter that into the Value data field.
Now I’m not entirely sure what will happen if you set it to a huge number… I’d stick with something like 20.
Note that the same tweak works in Windows 7 as well, even though the screenshots are from Vista.