XMMS is obsolete; in particular, it uses GTK+1.2 which is no longer available in most Linux distributions. It was removed from Debian in 2008: http://lists.debian.org/debian-devel/2007/07/msg00026.html

I don't know what the status of XMMS2 is, but it's a client-server model like MPD.

The GTK2 fork of XMMS, Beep Media Player, is reported by Wikipedia to be discontinued; the BMPx fork of BMP has also been removed Debian. Audacious is another Linux music player with Winamp skin support, it is actively maintained.

Perhaps somebody should do a Winamp2-compatible MPD client for nostalgia purposes.