I would use an early out test, should be faster on average depending on how large the Rect is compared to the screen res.
Function InRect:Int(x:Int,y:Int,x1:Int,y1:Int,x2:Int,y2:Int)
If x1>x Return False
If x2<x Return False
If y1>y Return False
If y2<y Return False
Return True
End Function