For the PCI Radeon 7000, you can flash a PC card with the Mac ROM, that's probably the cheapest route. To make a long story short, get a 32MB ATi OEM card... you need one that looks like this. Fortunately they're fairly common. There's also a variant with DVI, which you can use if you want DVI, but those cards are harder to find than the VGA-only ones. The reason you want an ATi OEM card is because they can be directly flashed with the Mac ROM, while most third-party cards either require additional steps or don't work at all.
I can't remember where I downloaded the ROM from... if you can't find it, lemme know and I'll send you a copy along with the flashing tools and such.
As for the OrangePC card, yeah, you basically hook it up like you would a Voodoo card. Of course you'll need the software and such to go with it, which seems to still be available here.
Being an old dick again Sly That card was installed down at the bottom and the card I was looking at was immediately installed above it.
And that card looks absolutely nothing like a Voodoo1 either. Hell, that card doesn't even have a VGA passthrough port on it.