Multiple PC Video Players?

No you can have as many video players as you want/need.

I have about 8.....no problems. Just make sure the right file types open with your specified player.

Im pretty sure having more than one anti virus will not hurt the computer, although there is likely to be conflicts. Having more than one media player, will not do any harm at all.

Video players (like you mentioned) are for playing videos. Ant-virus programs are for protecting your computer from Viruses/Spyware i.e. worms, trojan horses, rootkits, etc; Examples are Ad-Aware, Trend Micro, or McAfee (stay away from Norton or AVG).You must pay a subscription per year to have them, usually $25-$35, but it is more than worth it, trust me. and no it does not hurt to have more than one anti-virus program, I recommend 2 or more because one may catch something the other doesn't

relies upon whats ur aiming for even as u say reproduce different videos and audios, u can take heed to 2 sound information on a similar, i desire u can cause them to out nonetheless lol besides for the video u will want a video card with 2 DVI output, or mix of DVI and VGA output with the intention to apply 2 video demonstrate instruments on one computer, or u might want to apply SLI or xFire setup for 4 video demonstrate instruments or 3 or in spite of u get the conception, having a core2duo skill no longer something, except ur going into heavy video enhancing and rendering animation from adobe after effects or possibly 3D animation rendering for the audio u can use adobe audition or fruitloops to make sound, if ur going into audio and video enhancing i might want to purchase m-audio soundcard with a medium nvidia video card, would not propose ATI because they're ability hungry and dont grant

for the video players it not harmful to your computer

you can use as many as you want =)