Well, I'm no super game freak, but the Multi-User Dungeon (MUD) probably is dying out, slowly. Everyone's so into MMORPGs now! I've only seen one mud maker and that is MudMaker.com! I've tried it, but it's actually pretty boring. It doesn't seem to have a whole lot of capabilities like MMORPGs can. It might just be that site, but that's what I'm going by.
What they mean by "it has viruses" is that some of the things you download off of Limewire might come with a virus, not the program itself has a virus. I think that's what they were trying to say. Be careful what you download from it!