I have been using a PCI-E motherboard and video card here at work since late last year. I highly recommend them.
However, most people will agree (a few still don't) that an nVidia Quadro card is the way to go. "Gaming" cards just don't cut it unless you never open more than 4-5 files at a time. I am running a PNY Quadro FX1300 (PCI-E) with great results.
As far as which Quadro is right for you, it ultimately depends on what you are doing. My theory has always been to basically get the highest one that your budget will allow. It will last a lot longer for you for future SW versions. But the lower end Quadro cards (such as the FX540) has been confirmed by many to work well for simpler stuff.
There is also the option of using a cheaper GeForce gaming card and hacking it to a Quadro card using the soft-Quadro hack. I personally can't confirm how well this works. But I have read that many people have had good luck with this. I am considering doing this myself on my a new home computer that I am currently spec'ing.