If using SKS6 I believe you go, edit start menu,more programs mouse over image,Text tab, text color box.
If using SKS5 go, "XP taskbar",Click on "Programs" section of the start menu in the preview window *this will open the attributes for that section of the start menu*, on the right in "attributes" section scroll down til you see "text settings", if not expanded already, expand it by clicking the [+], then select "text color", you can either change the value to one already there in the "Value dropdown box" section below, or edit the color directly in the same section just below the colors value box.
I hope this helps 