Best Headphones for music

I know this is a very debated topic but let me make it easier to solve.
I am looking for a very high quality set of headphones. the will be used for music, and movies as well as audio editing and video work but mostly music related.

but here is the catch, I have a very nice Xfi sound card in my rig and I have been enjoying the "crystallize" and"cmss-3d"
both make my music sound allot better. now the only thing hindering it is a need for a good set of headphones

Will getting a 5.1 pair help? in a similar topic on this thread about a "gaming" headset I notice people didn't like certain aspects about the Medusa 5.1

Whats the best headphone set I can get that will really put my xfi cards features to use?

by the way..my range is around 100 but cheaper is appreciated

thanks so much