Wayne

hey, i got to play my gta iv for vista. but not working. and i click right to GTAIV shortcut, and i go to properties and go to compatibility. so i wanna run gtaiv program in compability mode for: (WINDOWS VISTA SERVICE PACK 1) but in my properties compability list just run for:
-windows 95
-windows 98 /windows me
-windows NT 4.0 (service pack 5)
-windows 2000
-windows XP (service pack 2)
-windows server 2003 (service pack 1)

weird! my gta iv told me for run gta iv program in compability mode for: windows vista (service pack 1)
my windows is real windows VISTA!! in my compability just windows server 2003, xp, 98, 95, and more! but why in my compability is no Windows vista?? help me please!! thanks!