Would you clarify what you mean by DJ system? If you are looking for a sound system that a DJ could control for parties and such, check out eBay and search for complete MP3 DJ system. Also check out visiosonic.com, alcatech.com, and mixmeister.com.
You can cross fade with Winamp and most players. I prefer MPXPLAY a DOS solution because you don't have to lug around a 200 meg cartoon interface for something you are just going to listen to. You select from the playlists by song number or it will do random play. It does have a mode that allows stacking up the songs you want to play.