Log onto MyUCLA. On the left hand toolbar, there is a GPA Calculator under "Academic". There are dropdowns that you can select your prospective grade, and calculate cumulative/quarter GPAs.
You cannot calculate a GPA 2 quarters from now. You can only calculate GPAs for courses you are/have enrolled in, meaning the furthest you can go is Winter 08 (as of now).
you can do it this way - GPA is calculated by total grade points divided by units taken. For each class you take your grade points are given by this formula i.e. for an A- in a 4 unit class you would get 3.7 * 4 units points. Add it up with the rest of the classes, divide by number of units total and that's your GPA.
You can also Google a GPA calculator like this one. Is that what you were looking for? It might take a while for you to input all your grades, but you got time.