Oh deary me, muchos paranoia and BS.
1) you should have good firewall and antivirus software on your PC. If you keep this up to date and run regular scans you should avoid any catastrophes.
2) If you're running Windows you should keep it up to date, sad but true MS operating systems are flawed from the box and are the predominant desktop OS, therefore they are targetted far more than others. Use Windows Update.
3) If you're running IIS, file & print sharing, or any other services that listen to requests from the internet DISABLE THEM BEFORE RUNNING GAMES because (quite apart from being not very secure) they will periodically sap your bandwidth. Very periodically if you're mad enough to be hosting a popular web site on your gaming PC.
4) Your copy of AoM and ESO (and thus all online ESO games) communicate using a proprietary messaging protocol defined by ESO, on a pre-defined numbered port. It is not possible for someone to send files (i.e. viruses) down this port unless they somehow hack ESO's servers. I believe the only file the protocol will accept will be a patch. Just guessing but an informed guess, I'm an IT consultant. If ESO's servers were hacked I'd guess ESO would bring them down instantantly until the problem was resolved, much as any other business would (or should).
Stop worrying. This ###_xile_### guy is some lame wannabe hacker 12 year old with a packet sniffer who thinks he's Neo.
YOU CANNOT CATCH A VIRUS FROM PLAYING AOM ON ESO - I'd stake their reputation on that.
mmmmm... beeeeeer....