Occasionaly when I search for a song i'll see exactly what I typed in but as a search result and an .mp3 file. Are these viruses?

What are .dat and .bak files that come in my limewire folder after downloading a song? I did not open them at all and deleted them in paranoia. Are they viruses?

Now here is something funny I encountered. What is it with seeing exactly what you typed in but it has something at the end "xxx hot sexy naked"?
Like i'll search numb(the song from linkin park) and see "Numb xx hot sexy naked". Are these viruses? I havent even touched those search results as they most likely have a virus.

Thanks again all!