I don't think nVidia or ATI/AMD's drivers will care at all if it's a PCI, PCI-X, PCI-E, or AGP card, but someone correct me if I'm wrong. If you've got an ATI/AMD or nVidia card, I would think you'd be fine, even with an AGP card. Otherwise, if you're not worried about gaming, you could probably just get a PCI card. A few still exist out there.
Thanks for your response. My experience is that even with the brands you mention, WIN7 driver support for AGP video cards is limited. I can't get by with a gaming card or a generic low-end card since I'm doing photo editing.
Almost seems like the math ($) points to buying a new computer with WIN7 already installed and with a (hopefully) good video card. Too bad because this Intellistation is a beautiful machine that will last forever.