Is there a media-player in Linux?

Yes, for th elongest time this was linuxs weak point, however now, with the advent of Mplayer, and the nature of the linux users to break the rules (copyright etc) Linux is even better now than Windows for media content.

Mplayer allows Real Video, all standard Windoes Media Player files, as well as those codcs that only Quicktime would touch. . . . and DVDs of course

How about the Java, Shockwave and Flash applets?

Mozilla was born out of the ashes of Netscapes death throws (from which it was resurrected. . . by Mozilla). Netscape was giving up, released all their source code, then the Linux crowd got a hold of it, reworked it, released it as something better, and Netscape saw what happened and decided not to give up, repackaging Mozilla as Netscape. Therefor Mozilla will take all standard netscape plugins for Flash and Java, probably shockwave too. . .

BTW: Mozilla does a much better job of packaging than Netscape. As far as mail programs, I used them in beta. They were user friendly but trashed a few emails. Its been years since that and with Mozilla out of its infancy Im sure the mail program is rock solid.

Also I would suggest the Mozilla Firebird Browser. Its lightning quick according to a friend of mine who I turned onto linux (I myself barely have time to devote here, much less Linux so I cannot attest firsthand to this)