I've been in a place where I install OS X on unsupported Macs ...
Your budget is $50 and you're asking about cards for video professionals and pulling a card out of an old DELL to flash? The best card would be the one you can spend the most on within your budget. Your budget doesn't really give you many options though. You also seem to be ignoring everyone in this thread.
I'm not ignoring anybody, but just throwing out a card number doesn't give me a reason to buy one. I may go up in budget a little, but that defeats the purpose of what I'm trying to do. I'm trying to take a 1,1 and for a little bit of upgrades make it close to an ashtray as possible. I really need to understand what the differences in the cards are, as far as when they were created, performance specs, etc. Also, if there is a cheaper PC version that isn't flashed then I might go that route and flash it myself to work with mac. I'm trying to find the best card that is the latest version for the least amount of money that will appeal to video professionals. So far nobody has addressed that.