While the card manufacture is important, I think the processor used more important. I've been using a Visiontek 4X AGP with Nvidia's GeForce 256 for over a year now. It's great!
I'm building a new rig: AMD Athlon 1.333, running on a AMD 761 chipset 266MHz and DDR support. In addition, I'm upgrading to a a GeForce2 GTS DDR by LeadTek. I chose them over VisionTek simply because of cost and availability.