Buying A Music Card

How about noise canceling headphones? Are they any good for mastering?
I tried Bose QC15 today at Best Buy and I have to say that for the first time I was actually pretty impressed with their noise canceling capabilities. The price is pretty steep but since I was looking for noise canceling headphones for a while now (I live next to a very busy street and with window open it’s pretty loud here), maybe I can kill two birds with one stone and have noise canceling headphones that are good for mastering?

Don’t go with Bose.

Any closed-ear 'phones are going to cancel out ambient noise. I can’t hear a thing when I’m wearing my HD-280s.

Since Christmas is coming, maybe I will actually spend a bit more on this. In that case, could you recommend some good speakers? Something I can do mastering on.

So far I saw these recommended:
KRK ROKIT POWERED 5 GENERATION 2 : 149€
ALESIS M1 ACTIVE MK2 : 149€

Anything else?