Is it wise to install norton on a PC which has mcafee?

No it is not. The two programs will probably interfere with each other. For example norton's firewall might think some mcafee componets are malicious and block them. You know the old saying two is better than one. Well when it comes to to antimalware software this maxim does not apply. Having mcafee and norton actually make you more vulnerable. So chose the one that best meets your needs and get rid of the other one.