I did see one difference in the Norwood card. The core is factory overclocked from 250MHz to 400MHz. Which is a pretty hefty overclock. That was the difference in price, plus the ATI was on sale. Which makes sense since the "built by ATI cards" are usually more expensive.
But when I take out the car it sys ATI on it, maybe I shoudl go return it for the 70 dollar one if it's 3rd party company
Since the Norwood card is overclocked you will get better performance out of it. And since it was overclocked by the factory you wont have to worry about the warranty be voided as opposed to OC'ing it yourself.
I'm with Saph, if your happy leave well enough alone.
8 Pro 64bit
AMD FX 8350
Asus Sabertooth 990FX R2.0
16GB G.Skill Sniper 1866MHz
OCZ Vertex 4 128GB SSD
HDD's 750GB x2/500GB/250GB
2x XFX 6870 1GB
12x BD-ROM
PC P&C 750W PSU
Cooler Master HAF 932 Red LED
CM Hyper 212 EVO w/2x SickleFlow 120mm Red LED
Logitech X540 5.1 Surround
2X Acer 23" LED - Eyefinity: 3840x1080
"The significant problems we face cannot be solved at the same level of thinking we were at when we created them."
- Albert Einstein