Right-click the start button, properties, customize
You'll find boxes in both the classic and XP start menus to put RUN on
the start menu. With the XP menu, it's under the advanced tab. Apply
and okay your way out.
You can also access Run via the windows key plus r, although I don't
know if this is practical for your situation. The windows key is
between the control and alt button, with the Microsoft flag.
