XPlite and 2000lite use the standard Windows navigation keys.
TAB changes the focus to the next control
SPACE selects or deselects checkboxes and items in the Add/Remove options tree.
ESC When veiwing the Add/Remove Components tab opens the control menu to allow access to the controls that are located above the options tree.
Show All (expand tree)
F1 Context Sensitive Help
Ctrl-P open/close the User Preferences and System Log dialogs.