dear lazyweb: headphone recommendations

Hey Folks,

So, I'm doing a bunch of work over the next several months in a relatively loud environment compared to most of the places that I've worked in the last 10 years or so. I've got an ipod and a pbook that are both full of mp3s, but I need a good pair of headphones to go with them.

Any recommendations for headphones? The key things for me is:
1) they should do a good job o blocking environmental noise
2) i have a really big head
3) they should be of somewhat high quality. I have good, but somewhat damaged hearing. I like to play music at a low volume, so I can hear the details better.