Rajee, to simply put it, once you put in your 64, you will never want to go back to an intel. You will notice a significant difference in your performance. Especially with photoshop. The hyper threading? Don't need it. AMD was designed for multitasking!
One thing people fall for is belief in the myth that a higher gigahertz means a faster computer. That's why AMD is thought by "non-computer people" to be a slower processor. The truth is that most of AMD's processors are hovering around 2-3 gigahertz while intel is nearing 4. In almost every benchmark I've seen, though, AMD beats out intel. They handle data in completely different ways.
Alright, I'm going to be quiet before I start drawing ASCII chip diagrams for comparison. 😛
Anyways, I recently upgraded from an intel 2.4 gigahertz P4 to a 2.2 gigahertz 3500 athlon 64, and there is no comparison. The intel is blown out of the water, dragged to land, then shot repeatedly! Don't worry, it won't let you down! Good luck!