1st - Ati will undoubatly have strict quality controls that it will force on those manufacturers. And if you are ever concerned still, just buy the ATI branded one instead of the other card makers.
2nd - I think ATI can easily keep up with nvidia. They are sorta like AMDs fight against intel. AMD use to just stay in the value and inagrated market with Intel in the high end. Now the athlon is kickign butt. I think same thing here. ATI was mainly lower end value and intagrated and now with the radeon and soon the radeon2, they are kicking and will kick butt in high end. Also with the superb expereince that ATIs recent aquasition of ArtX, im sure they will soon (after this soon comign smaller one) release a great inagrated chipset to fight the nForce as well.
Besides, nothing still beats the bang for the buck i have so far gotten out of my All-in-Wonder radeon.
Its a tivo, video card, campture card, tv tuner, etc...etc...all in one.
Thats what I all value. I dont care about getting 300fps in quake3. What I do want is my money to be well spent.