Yes Built By ATi (BBA) cards are good. Asus, Saphire, Gigabyte are also good. Powercolor and GeCube are not so good.
400/400 was refering to the Core speed in MHz and the memory Speed. A real 9600 pro is clocked 400 MHz core / 600 MHz memory. The Powercolor EZ model has cheap ram and is clocked 400 core / 400 memory. If you buy the 9600 pro, you want a 400/600 card.
The 9500 pro is clocked different (lower). But it is an 8 pipe card that outperforms the 9500 pro. The 9500 pro is harder to OC, but it can be done. I believe the 9600 Pro should overclock better, although I may get jumped on for saying that. ANyway, if you trust ebay, $100 for a Radeon 9500 Pro is a true bargain. I have a BBA R9500pro; very nice card.
ABIT IS7, P4 2.6C, 512MB Corsair TwinX PC3200LL, Radeon 9800 Pro, Santa Cruz, TruePower 430watt