virus

You should NOT run McAfee and Symantec at the same time. If you are going to run Symantec remove McAfee first - it will not be harmful to the computer. Just uninstall it from add/remove programs.

I have found that removal of MOST industry leading ANTI-VIRUS software does NOT simply uninstall from ADD/REMOVE I  am certain of Symantec Endpoint Protection. it is best to consult the software home page and download a removal tool I know Symantec has one not sure of McAfee.  Problem is they put folders in SYSTEM32 and other "secret" locations. As far as running them at the same time Not a good Idea althogh I have seen it done. Ifyou wish to test them both get a trial of  the windows
VMWARE version and run them  on 2 different versions of your OS or maybe try a dual boot.

get rid of BOTH of them and download AVAST ( www.avast.com), the home version is free and it is one of the best AV programs

Cheers

Liquid

Norton/Symantec removal tool:

http://us.norton.com/support/kb/web_view.jsp?wv_type=public_web&docurl=20080710133834EN&ln=en_US

McAfee removal tool:
http://service.mcafee.com/FAQDocument.aspx?id=TS100507

Replacement AV for either:

http://www.microsoft.com/en-us/security_essentials/default.aspx and
http://www.malwarebytes.org/

But what is going to give you the less amount of trouble..I wanted to comment on this question but Younghv had the right on answer!!  Why would you pay for trouble!!!...In fact why would you pay for double trouble..Do you know why those solutions have to pay to plant themselves on OEM products and then you end up having to take a crow bar to get rid of them!! I guess propaganda wins again!!

@nobleit,
I don't understand your answer selection.

The comment to which you awarded all the points starts with the phrase: "Above experts are correct...", yet you ignored all of us.

Would you care to explain your rationale please?

younghv is correct.  I was just expanding on the other answers - I will certainly not take offense if you decide to award points differently.