My friend recently bought a Corolla 2002, and he had a similar problem. When he shift the car in Drive, (as it would be 1st gear in case of Manual), the car would make a Ghuurrr, sound. Specially if the AC was ON the sound would be louder, but it will go away, as soon as the car is rolling fast and in higher gears. The Car dealership diagnosed that it is BELT TENSIONER. Almost all the corollas experience this problem. Belt Tensioner fails alot in Corollas.
But this problem is not just isolated to Corollas. Any car which makes this sound, specially at the starting up and putting in 1st gear, and if the sound goes away at higher speeds, it is most likely due to Serpentine Tension. If the Belt Tensioner is weak, it needs replacement. In US, the Belt Tensioner Brand New, can cost as much as $200, OR About Rs. 12,000.
So, this is just my observation. Have your car check by some reputable mechanic. Otherwise, there are alot of mechanic out there, that want your money fast, and will tell you all the things that are not wrong, and will replace the parts that don't need any replacement, just to make money off of you, and many times, the original problem still remains.
so, be sure to see a reputable honest Mechanic, or some authorized service station of auto dealers, there must be some, in Pakistan.