首先添加以下几个源到/etc/apt/sources.list（因为不知道具体是哪个源起了作用，所以最好就全加进去~_~）
# deb http://tonelli.sns.it/pub/mplayer/etch ./
# The Opera browser (packages)
deb http://deb.opera.com/opera etch non-free
deb ftp://ftp.nerim.net/debian-marillat/ stable main
# (00:24:00) AnThOnYhO: 这三个是w32codecs的源
deb ftp://ftp.nerim.net/debian-marillat/ sarge main
deb ftp://ftp.nerim.net/debian-marillat/ sid main
deb ftp://ftp.nerim.net/debian-marillat/ etch main
deb http://debian.cn99.com/ubuntu-cn dapper main
# deb http://tonelli.sns.it/pub/mplayer/etch ./
# The Opera browser (packages)
deb http://deb.opera.com/opera etch non-free
deb ftp://ftp.nerim.net/debian-marillat/ stable main
# (00:24:00) AnThOnYhO: 这三个是w32codecs的源
deb ftp://ftp.nerim.net/debian-marillat/ sarge main
deb ftp://ftp.nerim.net/debian-marillat/ sid main
deb ftp://ftp.nerim.net/debian-marillat/ etch main
deb http://debian.cn99.com/ubuntu-cn dapper main
接下来sudo apt-get install w32codecs 就行了。