The ATH-A900 is made by Audio Technica, and only available in the states through audiocubes.com as it's an import. But many, many people on these boards have bought them from there.
The QC2 is very possibly the best on the market for noise cancelation, so if you want something for flying and can't stand the noise, that's a good option. Me, I flew this year with my HD280s, sitting right next to the rear side jets, and I was perfectly happy with the result. Especially when the 280's were only $75.
For standard computer noise, any closed can will probably do the job just fine if you are capabable of even remotely ignoring the little noise that might be left. For TV and people noise, active cancelation can hurt more than help, though I don't know how the QC2's are in that respect. Active cancelation involves outputting noise to cancel noise, which means a slight delay due to processing. For constant noises this works well, but when someone is talking or the like it can introduce added distortion from the cancellation process.
To the original poster I agree with two sentiments: If you like them, enjoy them, and for goodness sakes, avoid this thread.
Otherwise, get a normal closed pair of anything that sounds good to you for home, and something else portable for the bus and such.
And get some switches to mount on the front of your case for those fans. If you watch your temps closely and you aren't doing bad, you might grab a Zalman throttle for the CPU fan too. You don't need them except when your gaming (and you probably don't even need all of them then), and when you're doing that you're too involved to care about a little noise. At least when you put everything on switches, you only have to have the hurricane blowing when you are showing off.
If all your noisiest fans are on components (video card, cpu, power supply), you may be happier overall investing in quieter soulutions for each of those (heat-pipe vid heatsync, quiet running power supply, quieter/larger cpu fan or even fanless cpu heatsync...) because that will improve your working environment overall, and done well, won't affect your performance.
Have fun with whatever you do.
dev*