To reduce the time it takes for the Start Menu to display the next tree as the cursor moves over it, edit:
HKEY_CURRENT_USER/Control Panel/Desktop
Double click on MenuShowDelay and set it to 100.
You will need to reboot for this to take effect.
I found that Win XP has that in its' registry too. Mine has its' default setting on 400. Maybe it works for it too. I haven't tried it.