I've got the standard 6600 and I've found a Quadro FX4500 on eBay, but its branded as a Dell unit. I'm just wondering whether this matters at all or whether I should just buy it and install it? Would there be any kind of firmware variations that wouldn't be compatible with OSX? I'm running Leopard 10.5.8.

The main reason I want to upgrade is that the 6600 is driving me crazy, I can't render 1080p ProRes edits in Final Cut Pro 6. Which sounds odd, but a window pops up saying that it can't render with the current graphics card. Any ideas?

Thanks in advance! :)

Absolutely positively no. Graphics cards for PPC-based Macs require different firmware than those for Intel-based Windows computers.

OK cheers! Found a Mac one in the USA that I'll hopefully get shipped to here in the UK.