Eh, not disputing the experiences that others have had, but merely citing my own personal experience.
I'm currently using a Creative Labs Blaster PCI Flash56/V.90 modem. The chip is made by Conextant. This is my second modem from CL using chips from Conextant. I've had zero probs. The modem chip is "flashable" so you can update it when new firmware/drivers (I know what the stuff does, just don't know the proper terminology in this case) come out. I paid $40 for mine. You can probably get it cheaper. Remember, when it comes to electronics, most of the time cheap price = POS component. Well, that's my $.02.