You need to edit you ~/.gtkrc-2.0 file to include the following:

style "modpanel"{
       fg[NORMAL] = "#FFFFFF"
}
widget "*PanelWidget*" style "modpanel"
widget "*PanelApplet*" style "modpanel"
widget "*switch-applet*" style "modpanel"
widget "*SwitchApplet*" style "modpanel"