Any of those Asus cards will work. I'd recommend against the third one (the fanless one) unless you have really good airflow through your case.
You may safely ignore the 400W recommendation in this case. Graphics card manufacturers overstate PSU requirements in the attempt (often vain) to account for all the liar-labeled junk still being sold. As I pointed out in my first post, a system build with a HD7750 in this summer's SBM cycle used a mere 150W PSU, and drew oinly 113W from the wall; that was after overclocking. You'll be fine with your current PSU.