2000 Mitsubishi Galant, 2.4L, ES, automatic.
The mileage on my car is 110000, I just bought this used car and the dealer told me that I will have to get the timing belt changed since it was supposed to be changed at 60000 miles(reccomended) and it wasnt done. I wanted to delay this expense for sometime. Moreover the engine is not giving any problems and no noise or anything. Is it advisable to do that or I should get it changed soon. 

There are typically two timing belts. The main belt is normally called the timing belt, and the other is usually referred to as the balance belt. The balance belt's job is to keep the engine balanced, which prevents noise and excess vibration in the car's cabin. The main timing belt makes sure the valves and cylinders move up and down in the correct timing frequency. If your timing belt were to break, the timing would be lost. This would cause the valves the smack into the cylinders. This would bend the valves and dent the piston heads. You would loose engine compression and the engine would not run at all. The only way to fix this would require a head rebuild; costing anywhere from $800-$1500.

A normal timing belt replacement may cost you between $300-$500. That is much cheaper than a head rebuild if your timing belt breaks. When a car hits the 100,000 mile mark, it's extra important to keep up with regular maintenance items. Mainly because your warranty is expired and all major repairs will have to come right out of your pocket. Spending a small amount and a little time for regular scheduled maintenance items will keep your car running for as long as you own it. In short, yes, get your timing belt replaced as soon as possible.
Good luck!