When it comes to updating anti-virus software, always do it. When you download the new versions, they should automatically replace the old versions.
About 3or4 months ago I installed the big three..(comodo firewall, spyware terminator and avira antivirus which all work like a charm. my os is vista basic. Comodo is now advising that I install the newer and improved version along with Avira antivirus. My question is should I install and if I do , do I have to uninstall my existing programs of avira and comodo. And where should i place all the existing files,any advice you can give me would greatly be be appreciated. Thank you Karen