By default it only recognizes the left and the right mouse button, but one can activate the 3rd mouse button (or middle mouse button), which ex. then can be used to perform a double-click.

Edit this DWORD registry key:

[HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Services \ PORT-TYPE-X]
NumberOfButtons=3

PORT-TYPE-X should be exchanged with the type of mouse connection: "BUSMOUSE", "SERMOUSE", or "i8042PRT" (PS/2).

More info MS KB102988
More info MS KB102989
More info MS KB102990