well i'm not too familiar with vista as i use xp myself and another language xp at that but... this might work
press and hold the windows key on your keyboard then press e so you get the explorer window
somewhere there you should see the c: drive, from there go into program or program files and then go into PlaneShift Steel Blue from there you must edit that xml file with notepad or wordpad, where it says false you should change it to true, save and exit the edit program, run the updater from the start menu and that should be it, don't think i can explain it any simpler sorry