Re: GTX 470 or HD 5870?
I haven't attempted raiding with max details on any graphics card yet @ 1920x using filtering. As you already noted, potential slow downs could be deadly. When I raid I disable many features to keep my FPS as high as possible. Currently I'm not willing to risk party members lives because of an odd slow down or pause. If I tag along in a non essential role in the future I may try it.
I have done the Crow's Nest and areas like it with all on and maxed without difficulty and that's not the same as some of the most demanding raids.
__________________Intel Core i7 920 @ 3.96GHz (1.36v)|Mushkin 998681 XP3-12800 (3x2GB)
ASUS TUF Sabertooth (X58)|ASUS GTX 580 DirectCU II (980|4604)|ASUS PA246Q
WD VelociRaptor 150GB HD (x2)|Pioneer DVR-2920Q|LG GH22LS30|Klipsch PM20 2.0
SilverStone OP1000-E|SilverStone TJ10-B|Thermalright U-120 Extreme|Win 7 HP x64