I have never shopped for a PCI express video card, so I don't know them all that well. My PC has Nvidia 6100 integrated graphics & an AMD 64X2 3800+ dual core. I thought I would ask here if anyone has any thoughts on what some good choices may be? Thanks

Almost all video cards out today are PCI express. A good starting point would be to know the rest of your system, what kind of budget, and what your planning to use it for.

Just to let you know if you didn't already that if you have a Dell, HP, or other manufactured PC there are large chances that you don't have a PCI-E slot...

Yeah we need to know your budget and also if you now and plan to use SLI. SLI is when you have two graphics cards that communicate with each other. One does the top half of your screen while the other the bottom half. Even if your mobo is SLI you don't have to buy two video cards right away...