I don't have experience with Bioshock, but I do have experience with the x1950 pro and a 22" monitor with 1680x1050 resolution. In fact I had 2 x1950 pro's in Crossfire. Things ran okay in standard 2D, but playing games led to some problems. After a short period of time, anywhere from 10-60 minutes depending on the game, the cards would hang while playing games. I tried them with Gothic 3, Dark Messiah and Oblivion. Things looked great, but I couldn't play for too long.
The big problem with these cards is overheating of the voltage regulators. This has been a huge problem with all of the manufacturers. I did read somewhere that ATI changed these boards a little to use analogue VR's instead of the digital ones they originally had to resolve the overheating problem. I can't vouch for that since I have since ripped mine out of my system, for good.
When they did work, the image quality was quite nice, and performance was decent as well (I have an E6600, 2Gb PC2-8000 RAM, in a liquid cooled system). I would recommend a single card, and go for the highest quality you can afford. I replaced mine with a single 8800 GTS, and things run much better now.
Good luck with your choice.