Without a shadow of a doubt.
it's the same price as the old 20"
DO IT!
The graphics/HD is worth it no matter what budget.
Games and Video Grapics apps love Video Memory
The difference between the two cards is that 2600Pro has a slower clock speed by 100Mhz, 2x slower in memory clock. Yet the 2600pro can access its memory 2x faster since it uses 128bit instead of 64bit and 3x pixels per clock (120Pixels per clock).
I say if you have the money for it, go, if you're going to be doing word processing and checking emails then nah. But it never hurts to be prepared for what ever interests you happen to pick up.